In early 2001, AJ Styles was offered a contract by WCW along with fellow wrestler Air Paris. Styles (renamed Air Styles) and Paris were placed in a tag team, which was named Air Raid. The team's gimmick saw both men dress in G-suits, with Air Raid appearing on Thunder three times. On the March 5, 2001 episode of Nitro, they were entered into a tournament for the newly created WCW Cruiserweight Tag Team Championship, but were eliminated in the first round by eventual winners Elix Skipper and Kid Romeo.
On July 9, 2001, Styles had his first WWF tryout match against Rick Michaels before the taping of Raw. Styles won with a Shooting Star Press but was not offered a contract.
Styles made two more appearances for the World Wrestling Federation (WWF) in 2002: on the January 26 episode of Metal (taped on January 21), in a losing effort against The Hurricane, and in a dark match prior to the January 27 episode of SmackDown! (taped on January 22), where he was defeated by Rico Constantino.
After not being on WWE television since his Metal match in 2002, Styles made his re-debut in WWE on January 24 at the Royal Rumble pay-per-view during the eponymous match for the WWE World Heavyweight Championship, entering at number three and receiving a loud ovation, thus establishing him as a fan favorite. Styles went on to eliminate Curtis Axel and Tyler Breeze, before being eliminated by Kevin Owens, lasting just under 29 minutes in the match. Styles then entered a storyline with Chris Jericho, with the two exchanging victories on both Raw and SmackDown, which ultimately led to an encounter between the two on February 21 at Fastlane where Styles emerged victorious via submission. After Fastlane, Jericho and Styles formed a tag team, dubbed "Y2AJ", and went on to defeat The New Day (Big E and Kofi Kingston) in two non-title matches. This led to a match for the WWE Tag Team Championship on the March 7 episode of Raw, which Y2AJ failed to win, after which Jericho turned on Styles and attacked him, officially ending their team. The two subsequently interfered in each other's matches, leading to Styles challenging Jericho to a match at WrestleMania 32, which Jericho ultimately accepted on the March 28 episode of Raw. At WrestleMania 32 on April 3, Styles lost to Jericho.
On the following episode of Raw, Styles pinned Jericho in a fatal four-way match also involving the returning Cesaro and Kevin Owens to become the number one contender for Roman Reigns' WWE World Heavyweight Championship to end the feud. In the weeks that followed, Styles united with Luke Gallows and Karl Anderson (later known as The Club) and an alliance, which Styles initially denied, was teased. At Payback on May 1, Reigns eventually defeated Styles by pinfall after the match was restarted twice (with Styles first winning by countout and then by disqualification), despite Gallows and Anderson's interference. Styles received a rematch against Reigns for the championship at Extreme Rules in an Extreme Rules match, but was unsuccessful due to interference from both Gallows and Anderson and The Usos (Jey and Jimmy Uso). The following night on Raw, Styles failed to qualify for the Money in the Bank ladder match at Money in the Bank against Kevin Owens. On the May 30 episode of Raw, he welcomed back a returning John Cena, only to attack Cena with help from Gallows and Anderson, turning into a villain as a result. This set up a match between Styles and Cena at Money in the Bank on June 19, which Styles won after interference from The Club. At Battleground on July 24, The Club took on Cena and Enzo Amore and Big Cass in a six-man tag team match, where they lost after Cena pinned Styles.
During the 2016 WWE draft on July 19, Styles was drafted to SmackDown in the first round of picks, being the brand's second pick overall, while Gallows and Anderson were drafted to Raw, splitting up The Club. Styles faced Cena once more at SummerSlam on August 21, defeating him cleanly. After his victory over Cena, Styles claimed himself to be the "new face of WWE" and "the Face That Runs the Place".
Due to his victory at SummerSlam, Styles immediately re-entered the renamed WWE World Championship picture and received another opportunity at the title at Backlash against Dean Ambrose. At the pay-per view on September 11, Styles defeated Ambrose to become the WWE World Champion for the first time after a low blow, also his first championship in WWE. Styles made his first successful title defense against Ambrose in a rematch on the September 27 episode of SmackDown Live after interference from John Cena. At No Mercy on October 9, Styles retained the title against Cena and Ambrose in a triple threat match after pinning Cena. On the October 11 episode of SmackDown Live, Styles suffered a humiliating non-title match loss to enhancement talent James Ellsworth after Ambrose (who was the special guest referee) interfered. SmackDown General Manager Daniel Bryan subsequently gave Ellsworth a WWE World Championship match against Styles on the October 18 SmackDown Live episode, which Styles lost via disqualification, but kept the title. Despite their animosity, Ambrose and Styles were part of Team SmackDown at Survivor Series on November 20, where their team ultimately prevailed, despite the two attacking each other and causing each other's elimination during the match. On the November 22 episode of SmackDown Live, Styles lost to Ellworth in a ladder match after interference from Ambrose, earning him a SmackDown contract and future championship match. At TLC: Tables, Ladders & Chairs on December 4, Styles defeated Ambrose in a Tables, Ladders, and Chairs match to retain the title after Ellsworth interfered and turned on Ambrose. Ellsworth explained that since he had already beaten Styles three times, he helped Styles because he wanted to defeat him again, this time for the renamed WWE Championship. On the December 20 episode of SmackDown Live, Styles squashed Ellsworth in under a minute to retain the championship and end their feud. On the December 27 episode of SmackDown Live, Styles defeated Dolph Ziggler and Baron Corbin in a triple threat match to retain the title. Styles lost the title to Cena at the Royal Rumble on January 29, 2017, ending his reign at 140 days.
On February 12 at Elimination Chamber, Styles competed in an Elimination Chamber match against Cena, Baron Corbin, Bray Wyatt, Intercontinental Champion Dean Ambrose and The Miz for the WWE Championship, where he lasted until the final two before being eliminated by Wyatt, who became the new champion. On the following episode of SmackDown Live, Styles failed to regain the title from Wyatt in a triple threat match also involving Cena.
On the February 21 episode of SmackDown Live, following Royal Rumble winner Randy Orton's unwillingness to challenge Wyatt at WrestleMania 33 for the WWE Championship, Styles competed in a 10-man battle royal to determine Orton's replacement and lasted until the final two, where the match ended in a draw after he and Luke Harper eliminated each other simultaneously. The following week, he defeated Harper to become the number one contender for the WWE Championship at WrestleMania, but Orton betrayed Wyatt and reclaimed his right to face him at WrestleMania 33, leading to a match between Styles and Orton on the March 7 episode of SmackDown Live, where Styles lost his number one contendership. On the March 14 episode of SmackDown Live, Styles ambushed SmackDown Commissioner Shane McMahon (who Styles blamed for him not challenging for the WWE Championship at WrestleMania) when he arrived at the arena and slammed his head into the window of a parked car. Afterwards, his boss Daniel Bryan spoke to Styles and—in storyline—fired him for his actions along with having security escort Styles out of the building. However, later that night, McMahon returned to the arena and announced that he would face Styles at WrestleMania 33, where Styles defeated McMahon. On the following episode of SmackDown Live, Styles shook hands with McMahon, thus turning face in the process.
On the April 11 episode of SmackDown Live, Styles defeated Baron Corbin and Sami Zayn to become the number one contender for the United States Championship. At Backlash on May 21, Styles lost his match against Kevin Owens for the United States Championship by countout after Owens got Styles' leg trapped in an announce table. At Money in the Bank on June 18, Styles was unsuccessful in winning the Money in the Bank ladder match. After Styles became once again the number one contender to Owens' championship, a title match was set for Battleground. However, Styles defeated Owens during a WWE live event at Madison Square Garden on July 7 to capture the United States Championship for the first time in his career. At Battleground on July 23, Styles lost the title back to Owens, but regained it two days later on SmackDown Live in a triple threat match also involving a returning Chris Jericho, thus becoming a two-time United States Champion. At SummerSlam on August 20, Styles defeated Owens to retain the title with Shane McMahon as the special guest referee. After once again defeating Owens two days later on SmackDown Live, Styles revived John Cena's U.S. open challenge, successfully defending the title two times on SmackDown Live against Tye Dillinger, who was also in a rivalry with Baron Corbin about who should answer Styles' challenge, leading to a triple threat match at Hell in a Cell on October 8, where Styles lost the title to Corbin who pinned Dillinger, thus ending his reign at 75 days.
After failing to regain the title from Corbin on SmackDown Live, Styles began a rivalry with then current WWE Champion, Jinder Mahal, by confronting and attacking him. During that time, Styles also appeared at Raw's exclusive event TLC: Tables, Ladders & Chairs on October 22, competing against Finn Bálor due to Bálor's original opponent Bray Wyatt not being cleared to compete in a losing effort. On the November 7 episode of SmackDown Live in Manchester, England, Styles defeated WWE Champion Jinder Mahal and won the title in what marked the first time the title changed hands on SmackDown since September 2003, claiming his second WWE Championship and becoming recognized by WWE as the first titleholder crowned outside of North America (Antonio Inoki had won the title in Japan in 1979, but this reign is unrecognized by WWE).
With the win, Styles replaced Mahal in the champion vs. champion match at Survivor Series on November 19 against Universal Champion Brock Lesnar, which he would go on to lose. At Clash of Champions on December 17, Styles defeated Mahal via submission in his first title defense. Styles' next feud came against Kevin Owens and Sami Zayn, whom he lost back-to-back matches to due to interference, which led to a handicap championship match at the Royal Rumble on January 28, 2018 which Styles won. Styles then successfully defended the title against Owens, Zayn, John Cena, Dolph Ziggler and Baron Corbin in a six-pack challenge at Fastlane on March 11.
Shortly after, Styles started a feud with Shinsuke Nakamura (who won the Royal Rumble and chose to challenge him at WrestleMania 34). At the event, on April 8, Styles defeated Nakamura to retain the WWE Championship, and after the match, Styles was subjected to a classless assault by his opponent, turning Nakamura into a villainand heating up their feud. Styles would go on to retain his title against Nakamura on three different events: Greatest Royal Rumble by double count-out, Backlash in a no disqualification match that ended in a no contest and Money in the Bank, where Styles ended the feud after winning a last man standing match. After a successful defense against Rusev at Extreme Rules, On August 14, Styles became the longest-reigning WWE Champion in SmackDown history, surpassing the 280-day record set by John "Bradshaw" Layfield.
During the summer, Styles started a feud with Samoa Joe, retaining the title at SummerSlam, despite losing via disqualification. Styles and Joe's rivalry continued following SummerSlam over Styles' wife, Wendy, where Joe claimed he would defeat AJ and become the "new daddy", leading to a rematch at Hell in a Cell, where Styles defeated Joe in controversial fashion to retain the title; Styles submitted to Joe during a roll-up, however, the referee did not see the submission and counted the pin allowing Styles to retain the title. Styles defeated Joe two more times at Super Show-Down by submission and Crown Jewel.
In October, Styles started to feud with Daniel Bryan. They would be scheduled to face each other for the title at Crown Jewel, but the match took place on the October 30 episode of SmackDown Live, after Bryan's refusal to work in Saudi Arabia. Styles managed to retain the title. On November 7, Styles surpassed the 365-day mark of his title reign, becoming the 8th man to have held the WWE Title for a continuous reign of a full year.
On the November 13 episode of SmackDown Live, Styles faced Daniel Bryan, where he lost the title following a low blow. This ended his reign at 371 days, which tied him for the eighth longest reign in WWE Championship history (along with Randy Savage's 1988–1989 reign). Styles received his rematch against Bryan at TLC, but failed to regain the championship. After TLC, Styles character was more aggressive, including attacking WWE Chairman Vince McMahon. He was referred to as "The Real AJ Styles", as opposed to Bryan's character "The New Daniel Bryan".
On the December 18 episode of SmackDown Live, Styles introduced Mustafa Ali as his protégé, resulting in Ali pinning Bryan in a tag team match also involving Styles and Andrade Cien Almas later that episode. Styles once again failed to win the title at Royal Rumble on January 27, 2019, after a returning Rowan attacked Styles when the referee was incapacitated and allowing Bryan to gain the win. Following the Royal Rumble, Styles gained another opportunity to earn back the championship after qualifying for the Elimination Chamber match to take place at the pay-per-view of the same name. However, Styles was unsuccessful at the event after he was eliminated by Randy Orton.
In the weeks leading up to Fastlane, Styles continued his feud with Randy Orton after being eliminated by Orton at the Elimination Chamber and a week prior in a gauntlet match. At the event, after Orton interrupted Elias, Styles hit Orton with a Phenomenal Forearm out of nowhere. This lead to a confrontation between the two on the March 12 edition of SmackDown Live in which Styles challenged Orton to a match at WrestleMania 35. The match was later confirmed a few days later where Styles defeated Orton. The next day, it was reported that Styles suffered an injury during his match with Orton and was sent home to recover. Styles did not appear on the Raw or SmackDown following WrestleMania, and it was reported to be a hip injury.
On the April 15 episode of Raw, Styles was drafted to the Raw brand in the 2019 WWE Superstar Shake-up. He teamed up with Roman Reigns and Seth Rollins to beat the team of Bobby Lashley, Drew McIntyre and Baron Corbin. The following week on Raw, Chief Executive Officer Triple H scheduled two triple threat matches with the winners facing each other to determine the next contender against Rollins for the Universal Championship. Styles defeated fellow draftees Rey Mysterio and Samoa Joe in the first triple threat match and faced off against Corbin, who defeated McIntyre and fellow draftee The Miz in the second triple threat match. Styles defeated Corbin to earn a Universal Championship match against Rollins at Money in the Bank. At the event, Rollins retained against Styles.
Styles returned on the June 24 episode of Raw, after a month of inactivity due to injuries suffered at Money in the Bank, defeating United States Champion Ricochet in a non-title match. On the July 1 episode of Raw, Styles failed to win the United States Championship from Ricochet. After the match, he attacked Ricochet with help from Luke Gallows and Karl Anderson thus turning heel in the process for the first time since April 2017. At Extreme Rules, Styles defeated Ricochet to win the United States Championship for a third time. On the July 22 episode of Raw, The Club was renamed "The O.C." ("Original Club"). Styles retained the title over Ricochet at SummerSlam. The next month at Clash of Champions, Styles retained against Cedric Alexander. Following his win over Alexander, Styles would begin a short feud with Humberto Carrillo, whom he defeated at Crown Jewel. On the November 25 episode of Raw, Styles lost his title to Rey Mysterio, ending his reign at 134 days.
At Super ShowDown in February 2020, Styles competed in the Tuwaiq Trophy Gauntlet Match, but was defeated by the returning Undertaker. Two weeks later at Elimination Chamber, Styles was defeated in a no disqualification match by Aleister Black after interference from The Undertaker. The next night on Raw, Styles challenged The Undertaker to a match at WrestleMania 36, which was confirmed the following week. At the event, Styles was defeated by Undertaker in a "boneyard match", where he was buried alive in a boneyard.
After a month long hiatus, Styles returned on the May 5 episode of Raw as a surprise entrant in a gauntlet match as he defeated Humberto Carrillo, earning him a spot in the Money in the Bank ladder match at Money in the Bank. At the event, Styles was unsuccessful at capturing the briefcase. Following this, Styles was officially traded to SmackDown as he was announced as a participant in the Intercontinental Championship tournament. He defeated Shinsuke Nakamura in the first round and earned a bye to the finals after his scheduled opponent, Elias, was unable to compete. On the June 12 episode of SmackDown, he won the Intercontinental Championship by defeating Daniel Bryan in the tournament final. During the following weeks, Styles successfully defended the title against the likes of Drew Gulak, Matt Riddle and Gran Metalik. Styles then lost the title to Jeff Hardy on the August 21 episode of SmackDown, ending his reign at 70 days. At Clash of Champions, Styles failed to regain the title in a triple threat ladder match that was won by Sami Zayn.
As part of the 2020 draft in October, Styles was drafted back to the Raw brand. On the October 19 episode of Raw, Styles debuted a new bodyguard, Omos, before defeating Matt Riddle. At Survivor Series, Styles captained Team Raw to a clean sweep victory against Team SmackDown. Shortly after the event, Styles would begin a feud with WWE Champion Drew McIntyre. At TLC: Tables, Ladders & Chairs, Styles faced McIntyre for the title in a TLC match but failed to win as the The Miz unsuccessfully cashed in his Money in the Bank briefcase during the match. At the Royal Rumble, Styles competed in his third rumble match, but failed to win after being eliminated by Braun Strowman. At Elimination Chamber, Styles unsuccessfully challenged for the WWE Championship inside the steel structure after being the final man eliminated by champion Drew McIntyre. Following The New Day's record-breaking eleventh Tag Team Championship victory, Styles and Omos challenged the duo to a championship match at WrestleMania 37, which The New Day accepted. At the event, Styles and Omos captured the Raw Tag Team Championships and in the process, Styles also became the twenty-second WWE Grand Slam Champion. Over the following months, Styles and Omos successfully defended the titles in rematches with The New Day and against Elias and Jaxson Ryker before entering into a feud with The Viking Raiders. A match was made between Styles and Omos and The Viking Raiders for the titles at Money in the Bank; at the event, Styles and Omos successfully defended the titles against The Viking Raiders. After this, Styles and Omos began feuding with Riddle and Randy Orton, making up the team of RK-Bro. After weeks of confronting each other, a match was made between Styles and Omos and RK-Bro at SummerSlam for the titles. At the event, Styles and Omos lost the titles to RK-Bro, ending their reign at 133 days. At Extreme Rules, Styles and Omos took part of in a six-man tag team match that included The New Day and Bobby Lashley, in which Styles, Omos and Lashley lost. After this, it was announced that Styles and Omos would face RK-Bro in a rematch for the tag team titles at Crown Jewel. At the event, Styles and Omos once again lost to RK-Bro. At Survivor Series in November, Styles and Omos took part in a cross-brand battle royal, which Omos won.
After failing to win several matches over the following weeks, on the December 20 episode of Raw, Omos turned on and attacked Styles, ending their partnership and in the process, thus turning face for the first time since July 2019. Styles would cement his face turn when he made an appearance on the following episode of NXT 2.0, where he confronted Grayson Waller, the latter of whom disrespected him. Styles and Waller would eventually face off on the January 11, 2022 edition of NXT 2.0, with Styles getting the win. Styles then participated in the Royal Rumble match and entered at number one before being eliminated by Madcap Moss. The next month, Styles challenged for the WWE Championship at Elimination Chamber, inside the namesake structure, where he failed to win the title after being eliminated by eventual winner Brock Lesnar. On the February 28 episode of Raw, Styles accepted an open challenge from Edge for a match at WrestleMania 38, which resulted in him being attacked by Edge afterward, including Edge hitting him in the head with a chair several times. On the second night of the event, Styles lost to Edge. On the April 18 episode of Raw, Edge challenged Styles to a rematch at WrestleMania Backlash, which Styles accepted. At the event, Styles would lose to Edge due to interference from Rhea Ripley. Styles then aligned himself with Finn Bálor and Liv Morgan, and challenged the newly-formed Judgment Day, which consisted of Edge, Damian Priest, and Rhea Ripley to a six-person mixed tag team match at Hell in a Cell. At the event, they were unsuccessful.
Styles failed to qualify for Money in the Bank after losing to Seth Rollins on the June 13 episode of Raw, and in a last chance battle royal on the June 27 episode of Raw. On the July 4 episode of Raw, he defeated The Miz and was subsequently attacked by both Miz and Ciampa after the match, starting a feud between them. At SummerSlam on July 30, Styles distracted Miz by attacking Ciampa and causing him to lose his match against Logan Paul. On the August 1 episode of Raw, Styles defeated Miz and Mustafa Ali in a triple threat match, but lost to Ciampa later that night, failing to earn an opportunity at the United States Championship. On the following episode of Raw, Styles defeated The Miz in a no disqualification match to end their feud. On the August 15 episode of Raw, he faced Bobby Lashley for the United States Championship in a losing effort. In the following weeks, Styles would rekindle his feud with The Judgment Day (which now included Finn Bàlor and Dominik Mysterio), turning down numerous offers by Bàlor to join them. On the October 10 episode of Raw, Styles feigned joining The Judgment Day, leading to Luke Gallows and Karl Anderson returning to WWE and aid Styles in attacking them, reforming The O.C.. At Crown Jewel on November 5, The O.C. lost to The Judgment Day after interference from Ripley. Three weeks later at Survivor Series WarGames on November 26, Styles defeated Finn Bálor to end their feud. During a live event on December 28, Styles would suffer a broken ankle.
As part of the 2023 WWE Draft, Styles was drafted to the SmackDown brand alongside O.C. stablemates Gallows, Anderson, and Mia Yim, returning on the April 28, 2023 episode. On the May 12 episode of SmackDown, Styles won the right to compete for the newly established World Heavyweight Championship at Night of Champions by first defeating Edge and Rey Mysterio in a triple threat match, and then defeating Bobby Lashley, who had won a similar triple threat match. At Night of Champions, Styles was defeated by Seth Rollins in a match to crown the inaugural World Heavyweight Champion. Two days later on Raw, Styles interrupted Rollins to congratulate him on the win, and the two would go on to face Finn Bálor and Damian Priest of The Judgment Day in the main event in a winning effort.
Styles would then be involved in The Bloodline storyline, losing to Solo Sikoa on the September 1 episode of SmackDown after interference from Jimmy Uso. Styles' old rival John Cena would come to his aid, setting up a tag team match between him and Styles against Uso and Sikoa for Fastlane. However, Styles was taken out by Solo backstage, removing him from the match and being replaced by LA Knight. After a three-month hiatus, Styles returned on the December 15 episode of SmackDown and assisted Knight and Randy Orton in fending off The Bloodline before also attacking Knight. The following week, the O.C. greeted Styles but Styles blew them off for not coming to his aid when he was taken out by Solo Sikoa and Jimmy Uso. At SmackDown New Year's Revolution on January 5, 2024, Styles faced Orton and Knight in a triple threat match to determine the number one contender to face Roman Reigns for the Undisputed WWE Universal Championship at Royal Rumble. The match ended in a no contest after The Bloodline took out all three competitors; SmackDown General Manager Nick Aldis then announced that Reigns would defend his title in a fatal-four way match against Styles, Orton and Knight at Royal Rumble. At the event, Reigns pinned Styles to retain.
On the February 9 episode of SmackDown, Styles lost to Drew McIntyre in a qualifying match for the Elimination Chamber match following a distraction from LA Knight. At the eponymous event on February 24, Styles would interfere in the Elimination Chamber match by attacking Knight with a chair and performing a Styles Clash on him with it, officially turning heel for the first time since December 2021. During night two of WrestleMania XL on April 7, Styles lost to Knight. The following SmackDown, Styles participated in the Undisputed WWE Championship eliminator tournament, defeating Kevin Owens and Rey Mysterio in the semifinals. Styles defeated Knight on the April 19 episode of SmackDown in the finals to challenge Cody Rhodes for the Undisputed WWE Championship at Backlash France. At the event on May 4, Styles was unsuccessful in winning the title from Rhodes. On the May 31 episode of SmackDown, Styles delivered an apparent retirement speech and called Rhodes out to the ring, which was revealed to be a ruse after he attacked Rhodes and realigned with Gallows and Anderson. On the June 7 episode of SmackDown, Rhodes challenged Styles to an "I Quit" match for the championship at Clash at the Castle: Scotland, which Styles lost.
Styles returned as a face on the October 4 episode of SmackDown, where he was confronted by Carmelo Hayes. During a match between the two that night, Styles suffered an ankle injury, causing Hayes to win the match via referee stoppage.