On July 13, 2017, Baszler entered WWE's Mae Young Classic, defeating Zeda in the first round. The following day, Baszler defeated Mia Yim, Candice LeRae, and Mercedes Martinez en route to the final. On September 12, Baszler was defeated in the final of the tournament by Kairi Sane.
Baszler made her NXT debut at a house show on August 10, 2017, where she teamed with Billie Kay and Peyton Royce; they faced the team of Kairi Sane, Aliyah, and Dakota Kai in a losing effort. On August 12, she made her singles debut, defeating Zeda. On October 3, WWE officially announced that Baszler had signed with the company and started training at the WWE Performance Center. On the December 6 episode of NXT, a vignette aired teasing Baszler's televised debut. She made her televised debut by attacking Kairi Sane on December 27, and her televised in-ring debut on the episode aired January 10, 2018, defeating Dakota Kai by referee stoppage. Afterward, Baszler continued to attack Kai until NXT Women's Champion Ember Moon made the save. That led to a title match at NXT TakeOver: Philadelphia on January 27, where Moon defeated Baszler to retain the title, but was attacked by Baszler afterwards. Baszler received another title match against Moon at NXT TakeOver: New Orleans on April 7, where Baszler defeated Moon by technical submission to win her first women's championship in NXT . On the May 30 episode of NXT, Baszler successfully defended her title against Dakota Kai. She then began a feud with Nikki Cross, culminating in a match at NXT TakeOver: Chicago II where Baszler defeated Cross by technical submission to retain the title. Baszler then lost the title to Kairi Sane at NXT TakeOver: Brooklyn 4, ending her reign at 133 days. At Evolution, she defeated Kairi Sane by regaining and become the first-ever two time NXT Women's Champion. Baszler went on to defend her title against Sane at NXT TakeOver: WarGames, Bianca Belair at NXT TakeOver: Phoenix, and at NXT TakeOver: New York in a fatal four-Way match against Io Shirai, Bianca Belair and Kairi Sane, submitting Belair with a Kirifuda Clutch. Bazler had a brief feud with Shirai, whom she retained her title against at NXT TakeOver: XXV and on the June 26th episode of NXT in a steel cage match ending their feud. At NXT TakeOver: Toronto, she successfully defeated Mia Yim to retain her title. On October 2, Baszler successfully retained her title against Candice LeRae on NXT. On the November 1 episode of SmackDown, Baszler was the first NXT wrestler to invade the show, when she attacked SmackDown Women's Champion Bayley, Sasha Banks and Nikki Cross. Later that night, Baszler joined Triple H and the rest of the NXT roster as they declared war on both Raw and SmackDown, and vowed to win the Survivor Series brand warfare. At NXT TakeOver: WarGames, Baszler and her team lost against Rhea Ripley and her team in the first ever women's WarGames match. At Survivor Series, Baszler won the triple threat champions match against Raw Women’s Champion Becky Lynch and SmackDown Women’s Champion Bayley to win Survivor Series for the NXT brand. On the December 18 episode of NXT, Baszler lost the championship to Ripley, ending her reign at 416 days, making her the sixth longest reigning women's champion after Sensational Sherri's reign of 441 days. On the January 1 episode of NXT, Shayna Baszler earned the Female Competitor Award in NXT. She would enter the Women's Royal Rumble match at #30 on January 26 and go on to eliminate eight contestants, which tied the record for most eliminations in a Women's Royal Rumble Match, before being eliminated in the end by Charlotte Flair, who would win the match.
On the February 10, 2020 episode of Raw, Baszler appeared and attacked Becky Lynch, biting the back of her neck furiously. The following week, although still part of NXT, Baszler was announced as a participant in the Raw brand's women's Elimination Chamber match for a chance at Lynch's Raw Women's Championship at WrestleMania 36. At the Elimination Chamber pay-per-view on March 8, Baszler won the match to become the number one contender for the Raw Women's Championship, and also set a record, eliminating every other woman, in what was essentially a squash match. On the March 23 episode of Raw, Baszler was brutally assaulted by Becky Lynch with a steel chair during a sit-down interview. On the March 30 episode of Raw, Baszler attacked Lynch in the middle of the latter’s promo. At WrestleMania 36, on night one, Baszler failed to win the title from Lynch after a roll-up pin. On the April 13 episode of Raw, Baszler defeated Sarah Logan to qualify for the women's Money in the Bank ladder match for a chance at a championship match any place, and anytime. During the match, Baszler broke Logan's arm before Logan was released from WWE two days later. On May 10 at Money in the Bank, Baszler failed to win the contract. The next day on the May 11 episode of Raw, Baszler defeated Natalya. The next week, she defeated Natalya once again in a submission match.
After a two-month hiatus, Baszler returned to WWE on the July 13 episode of Raw, saving R-Truth and attacking Akira Tozawa’s ninjas before cutting a promo where she sent a warning to the women of the Raw roster. On the July 27 episode of Raw, Baszler interrupted Nia Jax. The two brawled and later on they had a match in which they fought to a double count out; they continued to brawl and even attacked some of the security. On August 3 episode of Raw, Baszler interrupted the SmackDown Women's Champion and Raw Women's Champion, and also WWE Women's Tag Team Champions Bayley and Sasha Banks in a backstage interview and punched Banks in the face. Later that night, they had a match which ended in no contest when Asuka attacked Bayley at ringside for her assault on Asuka's tag team partner, Kairi Sane, the previous week. Baszler then told Asuka that after she regained the Raw Women's Championship from Banks that she would be the one to take the title from Asuka. On the August 10 episode of Raw, Bazler appeared on the new Raw Underground segment, attacking three different women and winning her fight by submission. Over the next several weeks, Bazler would form an uneasy alliance with Asuka against Banks and Bayley, and continued her rivalry with Nia, turning face for the first time in her WWE career. At Payback, the unlikely alliance and tag team of Baszler and Jax defeated Banks and Bayley to win the WWE Women's Tag Team Championships, marking Baszler's first title since her main roster debut. However, the face run was short lived as during her reign as tag team champion with Nia Jax, both Baszler and Jax reverted back to heels by constantly bullying and putting Lana through the announce table for consecutive weeks, which led to the duo brutally attacking and injuring her, thus removing Lana from a Women's Tag Team Title match at TLC. On December 20, at TLC, Charlotte Flair was revealed to be the replacement of Lana, as she and Asuka defeated Baszler and Jax to win the Women's Tag Team Titles. On January 31, Baszler and Jax became record-tying two-time WWE Women's Tag Team Champions, defeating Charlotte Flair and Asuka on the Royal Rumble kickoff show. During their second reign as tag team champions, they would have simultaneous feuds with the teams of Naomi and Lana, Mandy Rose and Dana Brooke, and Natalya and Tamina. They would defend the titles against all of them on different occasions, but would be victorious in every bout. At WrestleMania 37, Jax and Baszler would defend the tag titles against Tamina and Natalya and would retain the titles. After multiple singles matches and tag team matches between the two teams, Baszler and Jax would lose the titles to Natalya and Tamina on the May 14 episode of SmackDown.
On the May 31 episode of Raw, Baszler would begin a feud with Alexa Bliss, claiming that the use of Alexa's "powers" are the reason why Jax and Baszler lost the tag team titles. A match between the two would then be scheduled for Hell in a Cell, in which Baszler lost to Bliss. After weeks of problems between the two, on the September 20 episode of Raw, her alliance with Nia Jax ended when she brutally attacked Jax after their match against each other.
As part of the 2021 Draft, Baszler was drafted to the SmackDown brand. In October, Baszler entered the Queen's Crown tournament, where she defeated Dana Brooke in the first round, but lost to Doudrop in the semifinals. She participated in the five-on-five Survivor Series elimination match at Survivor Series, eliminating Rhea Ripley before she was eliminated by Bianca Belair. She also participated in the Royal Rumble match at the namesake event on January 19, 2022, entering at number thirty, but was eliminated by Charlotte Flair. During this time, Baszler formed a tag team with Natalya and challenged for the WWE Women's Tag Team Championship, leading to a fatal four-way tag team match for the titles on the second night of WrestleMania 38, which was won by Sasha Banks and Naomi. On the August 5 episode of SmackDown, Baszler won a gauntlet match for the opportunity to face Liv Morgan for the SmackDown Women's Championship at Clash at the Castle, but failed to win the title at the event.
On the October 28 episode of SmackDown, Baszler attacked Natalya in a backstage segment, ending their partnership and aligning with SmackDown Women’s Champion Ronda Rousey in the process. The following week, with Rousey in her corner, Baszler defeated Natalya. At Survivor Series WarGames on November 26, Baszler helped Rousey retain her title against Shotzi. At the Royal Rumble on January 28, 2023, Baszler entered the titular women's match at number five, before being eliminated by Damage Control (Bayley, Dakota Kai, and Iyo Sky). On Night Two of WrestleMania 39, Rousey and Baszler won the women's WrestleMania Showcase fatal four-way tag team match (also involving Liv Morgan and Raquel Rodriguez, Natalya and Shotzi, and Chelsea Green and Sonya Deville). As part of the 2023 WWE Draft, Baszler and Rousey were drafted to Raw. On the May 29 episode of Raw, Baszler and Rousey won a fatal four-way tag team match for the vacant WWE Women's Tag Team Championship. On the June 23 episode of SmackDown, Baszler and Rousey defeated Alba Fyre and Isla Dawn for the NXT Women's Tag Team Championship to unify the two tag team titles. At Money in the Bank, Baszler turned on Rousey by attacking her and walking out of the match. Liv Morgan and Raquel Rodriguez took advantage and pinned Rousey to regain the WWE Women's Tag Team Championships. On the July 10 episode of Raw, after Baszler defeated Emma, Rousey came out and another brawl broke out. The following week, after defeating Nikki Cross in a match, Rousey called out Baszler from the skybox; Baszler then challenged Rousey to a match at SummerSlam. This started a slow face turn for Baszler as a result. Baszler defeated Rousey at SummerSlam by technical submission.
On the September 4 episode of Raw, Baszler defeated Zoey Stark by technical submission after Stark passed out to the Kirifuda Clutch. After the match, Baszler gave praise to Stark's toughness. In the following week, Stark ran out to save Baszler when Baszler was attacked by Chelsea Green and Piper Niven after Baszler's match with Green. At Crown Jewel on November 4, Baszler competed in a fatal five-way match for the Women's World Championship against Stark, Jax, Raquel Rodriguez and defending champion Rhea Ripley, but failed to win the title. On Raw Day 1 on January 1, 2024, Baszler teamed up with Stark for the first time to defeat Tegan Nox and Natalya to become the number one contenders for the WWE Women's Tag Team Championships.
During week one of NXT Spring Breakin', Baszler made her return to NXT as the trainer for Lola Vice as she prepared to face Natalya in an NXT Underground match the following week. Vice would go on to win the match. Following the win, the rivalry between the two teams continued, and on the May 14 episode of NXT, Natalya and Karmen Petrovic challenged Vice and Baszler to a tag team match on next week's episode, which was made official. Natalya and Petrovic would go on to win the match. Afterwards, Vice turned on Baszler and a brawl began between the two. NXT General Manager Ava would then announce a match between the two at NXT Battleground in an NXT Underground match. On the June 4 episode of Raw, Baszler and Stark challenged Bianca Belair and Jade Cargill to a WWE Women's Tag Team Championship match, which ended in a disqualification win for Belair and Cargill after Alba Fyre and Isla Dawn interfered. On June 9, at Battleground, Baszler was defeated by Vice.