In Summer 2017, Ripley signed with the WWE. It was announced that she would compete in the inaugural Mae Young Classic. Ripley eliminated Miranda Salinas in the first round but lost to Dakota Kai in the second round.
Ripley made her NXT television debut on October 25, 2017 episode of NXT, participating in a battle royal to determine one of the contenders for the vacant NXT Women's Championship at NXT TakeOver: WarGames, which was won by Nikki Cross.
Sporting a new look, Ripley competed in the second annual Mae Young Classic in 2018 and finished in the semi-finals, defeating MJ Jenkins, Kacy Catanzaro, and Tegan Nox before losing to Io Shirai. Throughout the tournament, Ripley displayed a new attitude, one of which declining to shake her opponent's hand before the match and more aggressive and remorseless from the previous year, establishing herself as a heel in the process.
Shortly after her participation in the Mae Young Classic, Ripley was announced as part of the women's roster in the newly created NXT UK brand. During the television tapings of the show in August (that aired throughout November), Ripley took part of an eight woman tournament for the inaugural NXT UK Women's Championship. She went on to defeat Xia Brookside in the first round, Dakota Kai in the semi finals, and Toni Storm in the finals to become the inaugural champion. With the win, Ripley also became the first Australian to ever hold a women's championship in WWE. In October, Ripley also competed before the first ever all women's pay–per–view, Evolution, where she successfully retained her title against Dakota Kai in a dark match (due to the tournament airing a month later). Throughout her championship reign, Ripley went on to fend off title contenders such as Isla Dawn and Deonna Purrazzo. At NXT UK TakeOver: Blackpool, she lost her title to Toni Storm ending her reign at 139 days. At the Royal Rumble, she debuted on the main roster by entering the Women's Royal Rumble at number twenty-four. She eliminated Kacy Catanzaro, Dana Brooke, and Zelina Vega before being eliminated by Bayley. For the most part of 2019, Ripley started a feud with a debuting Piper Niven over who's the most dominant woman in the NXT UK roster. The two finally squared off in a match on the July 3, 2019 episode of NXT UK where Niven defeated Ripley.
On the August 28, 2019 episode of NXT, Ripley made her return when she interrupted NXT Women's Champion Shayna Baszler. Swiping the microphone from Baszler before she could even talk, Ripley said that Baszler may have beaten everyone on NXT, but she hadn't beater her, signalling a feud between the two.
On the November 1 episode of SmackDown, Ripley and Tegan Nox were one of the many NXT wrestlers to invade the show, challenging Mandy Rose and Sonya Deville to a tag-team match, which Ripley and Nox emerged victorious. Later that night, Ripley joined Triple H and the rest of the NXT roster as they declared war on both Raw and SmackDown, and vowed to win the 2019 Survivor Series brand warfare. At NXT TakeOver: WarGames, she led Team Ripley (herself, Candice LeRae, Dakota Kai and Nox) to victory over Team Baszler (Shayna Baszler, Io Shirai, Bianca Belair, and Kay Lee Ray) in a WarGames match despite Kai betraying and attacking Nox. The following night at Survivor Series, she was part of Team NXT which beat Team Raw and Team SmackDown. She scored the victory for her team by defeating Sasha Banks. On the December 18 episode of NXT, Ripley won the NXT Women's Championship from Baszler. This made her the first female superstar to have won both the NXT Women’s and NXT UK Women’s Championships. She then successfully defended the title against Toni Storm on 25 January 2020 at Worlds Collide.
Ripley made a surprise appearance on the 3 February 2020 episode of Raw, confronting Royal Rumble winner Charlotte Flair and suggesting that Flair should use her Royal Rumble title opportunity to challenge Ripley for the NXT Women's Championship at WrestleMania 36. Flair appeared in the following episode of NXT to give her answer, but was interrupted by both Ripley and Bianca Belair, Ripley's future title contender at NXT TakeOver: Portland, and Ripley herself, with the two eventually teaming up and attacking Flair. At the aforementioned event, Ripley successfully defended the championship against Belair, and was attacked by Flair, who accepted Ripley's challenge. Ripley then lost the title to Flair at the second night of WrestleMania 36. The next day after WrestleMania, WWE announced that Ripley took hiatus from WWE. After a one-month hiatus, Ripley returned on the May 6 episode of NXT after Flair got herself disqualified in an NXT Women's Championship match against Io Shirai by attacking Flair. On June 7 at NXT TakeOver: In Your House, Ripley and Flair both lost to Io Shirai in a triple threat match for the NXT Women's Championship. On the July 1 episode of NXT The Great American Bash, Ripley defeated Aliyah and Robert Stone in a 2-on-1 handicap match by submission. On the November 18 episode of NXT, Ripley challenged Shirai for the NXT Women's Championship, but was unsuccessful. On the December 2 episode of NXT, Ripley was announced as a member of Shotzi Blackheart's team for the second ever women's WarGames match at TakeOver: WarGames.
On the first edition of NXT for 2021, New Year's Evil, Ripley competed against Raquel Gonzalez in a Last Woman Standing match in a losing effort. At the Royal Rumble, Ripley competed in her second women's Royal Rumble match, entering at number fourteen, where she ended up with seven eliminations and one of the final two in the match before she was eliminated by eventual winner Bianca Belair.
On the February 22 episode of Raw, a video package aired hyping up Ripley's official arrival to the brand. Ripley made her main roster debut on the March 22 episode of Raw, confronting Asuka after her match and challenging Asuka to a match for the Raw Women's Championship at WrestleMania 37. On the April 5 episode of Raw, Ripley attacked Asuka in their non-title tag team match against Nia Jax and Shayna Baszler, as a game of one-upping the champion. At WrestleMania 37 on night two, which took place on April 11, she defeated Asuka to win the Raw Women's Championship. On the Raw after WrestleMania, Ripley was scheduled to defend the title in a rematch against Asuka; the match ended in a no-contest after interference from Charlotte Flair, who attacked both Asuka and Ripley. On the May 3 episode of Raw, another rematch between Ripley and Asuka for the Raw Women's Championship was scheduled for WrestleMania Backlash. However, WWE official Sonya Deville added Flair to the championship match to make it a triple threat match. Ripley successfully retained her title by pinning Asuka at the event. A match between Ripley and Flair was then scheduled for Hell in a Cell, which Flair defeated Ripley by disqualification, thus Ripley retained her title. At Money in the Bank, Ripley dropped the title to Flair in another rematch, ending her reign at 98 days. Ripley failed to regain the Raw Women's Championship in a triple threat match against the champion Nikki A.S.H. and Flair at SummerSlam. In the following weeks, Ripley allied with Nikki A.S.H. as a tag team. On the September 20 episode of Raw, they won WWE Women's Tag Team Championship by defeating Natalya and Tamina. On the November 22 episode of Raw, Ripley and A.S.H. were defeated by the team of Carmella and Queen Zelina in a title match, ending their reign at 63 days.
On the March 7, 2022 episode of Raw, she teamed with Liv Morgan to defeat Queen Zelina and Carmella; their victory would add them to the Women's Tag Team Championship match at WrestleMania 38. At WrestleMania 38, Ripley and Morgan participated in a fatal four-way match for the WWE Women's Tag Team Championships, but it ended in defeat when Sasha Banks and Naomi won the titles. On April 4, the Raw after WrestleMania, Ripley and Morgan faced Sasha Banks and Naomi in a contender's match for the titles, which ended in a losing effort and caused a distraught Ripley to walk out on Morgan. Two weeks later, on the April 18 episode of Raw, they finally got a tag team match for the WWE Women's Tag Team Championships against Banks and Naomi, but it also ended in defeat. This led to Ripley arguing with, and then attacking Morgan and breaking up their team, thus turning heel.
On May 8 at WrestleMania Backlash, Ripley was revealed as a member of Judgment Day, by costing AJ Styles his match against Edge. At Hell in a Cell on June 5, The Judgment Day defeated Styles, Finn Bálor and Liv Morgan in a six-person mixed tag team match. The next night on Raw, Edge introduced Bálor as the newest member of The Judgment Day; however, Bálor, Priest and Ripley suddenly attacked Edge, kicking him out of the stable. Later that night, Ripley won a fatal four-way match to become the number one contender for Bianca Belair's Raw Women's Championship. She was scheduled to face Belair at Money in the Bank on July 2, but was pulled out of the match after being not medically cleared to compete; she was replaced by Carmella.
On the July 25 episode of Raw, Ripley returned from injury, helping Bálor and Priest attack the Mysterios (Rey and Dominik) in a backstage segment. Ripley accompanied Bálor and Priest to the ring for their match against The Mysterios at SummerSlam on July 30, which they lost after interference from a returning Edge. Despite interference from Ripley, Bálor and Priest lost to Edge and Rey in a tag team match at Clash at the Castle on September 3. After the match, Dominik attacked Edge and Rey, turning heel and joining The Judgment Day. On October 8 at Extreme Rules, Dominik, Priest, and Ripley helped Bálor defeat Edge in an "I Quit" match. After the match, Ripley attacked Edge’s wife, Beth Phoenix, with a con-chair-to. At Crown Jewel, Bálor, Priest, and Dominik defeated The O.C. (AJ Styles, Luke Gallows, and Karl Anderson) in a six-man tag team match after interference from Ripley. On the following episode of Raw, The O.C. introduced the returning Mia Yim as their solution to counter Ripley. Three weeks later at Survivor Series WarGames on November 26, Ripley's team lost to Yim's team after Becky Lynch pinned Dakota Kai in a WarGames match. On the November 28 episode of Raw, The Judgment Day defeated The O.C. in an eight-person mixed tag team match to end their feud. On the December 19 episode of Raw, Ripley challenged Akira Tozawa to a match after Tozawa splashed a beverage in Dominik's face during a tag team match between Bálor and Priest against the Street Profits. Ripley went on to win her first intergender match against Tozawa.
At the Royal Rumble on January 28, 2023, Ripley appeared at ringside during the men’s Royal Rumble match to assist her stablemates in their attack on Edge, only to be speared by Edge’s wife, Beth Phoenix. Later that night, Ripley won the women’s Royal Rumble match by last eliminating Liv Morgan. With this victory, Ripley became the fourth wrestler and the first woman to win the Royal Rumble as the first entrant. On the following episode of Raw, Ripley declared that she would be challenging Charlotte Flair for the SmackDown Women's Championship at WrestleMania 39. At Elimination Chamber on February 18, Ripley and Bálor were defeated by Edge and Phoenix in a mixed tag team match.
On Night One of WrestleMania 39 on April 1, Ripley defeated Flair to win the SmackDown Women's Championship. With this win, Ripley became the seventh women's Triple Crown Champion and the fifth women's Grand Slam Champion. At Backlash, Ripley successfully defended her title in her first defense against the Latino World Order's Zelina Vega. At Night of Champions, Ripley successfully defended the SmackDown Women's Championship against Natalya in a squash match that lasted 70 seconds. On the June 12 episode of Raw, the SmackDown Women's Championship was renamed to the Women's World Championship and Ripley was presented a brand-new championship belt. On the July 3 episode of Raw, Ripley defeated Natalya once again to retain the title. At Payback on September 2, Ripley helped Bálor and Priest win the Undisputed WWE Tag Team Championships after spearing Kevin Owens through the barricade. Later that night, Ripley retained her title against Raquel Rodriguez after a distraction from Dominik. On the September 11 episode of Raw, Ripley defeated Rodriguez in a rematch to retain the title after interference from the returning Nia Jax, who attacked Ripley after the match. At Crown Jewel on November 4, Ripley defeated Jax, Rodriguez, Zoey Stark and Shayna Baszler, who Ripley pinned, to retain her title in a fatal five-way match. At Survivor Series: WarGames on November 25, Ripley defeated Stark to retain her title. At Raw Day 1 on January 1, Ripley defeated Ivy Nile to retain the title.
On February 24 at Elimination Chamber: Perth in her home country of Australia, Ripley successfully defended her title in the main event against Nia Jax. On night one of WrestleMania XL on April 6, Ripley successfully defended her title against Becky Lynch. On the April 8 episode of Raw, Ripley was attacked in a backstage segment by Liv Morgan, during which Ripley legitimately injured her right arm. The following week, she was forced to vacate the championship, ending her reign at 380 days, tying Bayley's record as the longest-reigning Women's World Champion. During Ripley's absence, the storyline continued when Morgan began seducing Dominik, who resisted Morgan's efforts, but accidentally helped her win the Women's World Championship from Lynch at King and Queen of the Ring. Morgan also began interfering in The Judgment Day's matches, including helping Bálor and JD McDonagh win the World Tag Team Championship. After a three-month hiatus, Ripley returned on the July 8 episode of Raw, confronting Morgan and Dominik. At SummerSlam on August 3, Ripley was unsuccessful in regaining the title from Morgan after interference from Dominik, giving Ripley her first pinfall loss since May 2022. After the match, Dominik turned on Ripley and kissed Morgan, ending their partnership and fully turning Ripley face for the first time since April 2022. On the following episode of Raw, Bálor officially removed Ripley and Priest, who Bálor also betrayed by costing him the World Heavyweight Championship at SummerSlam, out of the group, cementing her face turn. During Priest's match against McDonagh, Bálor would ambush him along with the rest of The Judgment Day, until Ripley came out to save him. Ripley and Priest would afterwards embrace each other, thus staying together as a team, going by The Terror Twins. At Bash in Berlin on August 31, Ripley and Priest defeated Mysterio and Morgan with Ripley pinning Morgan despite interference from The Judgment Day. At Bad Blood on October 5, Ripley defeated Morgan by disqualification after being attacked by the returning Raquel Rodriguez. However, since championships do not change hands via disqualification or countout unless otherwise stipulated, Morgan remained champion.
On the October 29 episode of NXT, Ripley was attacked by Morgan and Rodriguez in the WWE Performance Center parking lot.