[6] Promoter Bob Arum told Ringtv that Stevenson would likely make his debut on a stacked card at the StubHub Center in Carson, California on April 22, 2017.

[7] Stevenson showed off his agility, defense and punching skills as he won his first professional fight against American boxer Edgar Brito.

[8][9] In an official press release on May 3, it was confirmed that Stevenson would make his Madison Square Garden debut on undercard of the Terence Crawford vs. Félix Díaz world light welterweight championship fight on May 20, 2017.

[11] Stevenson's third bout took place at the Pinnacle Bank Arena in Lincoln, Nebraska, again on the undercard of Terence Crawford, this time his unification fight against Julius Indongo on August 19, 2017.

[19] On the night, in front of 2,828 fans, Stevenson outboxed Gonzalez, winning a unanimous decision with all three judges scoring the bout 119–109 in his favor.

[25] In November 2020, Top Rank announced Stevenson would fight Toka Khan Clary (28-2, 19 KOs) on December 12 in a 10-round bout at The Bubble at the MGM Grand Hotel & Casino in Las Vegas.

Stevenson defeated Clary convincingly, winning the fight by a wide margin on the scorecards, with all three judges scoring the contest 100–90 in his favor.

[30] After improving to 15–0, in April 2021, it was announced that Stevenson would next fight Jeremiah Nakathila (21-1, 17 KOs) on June 12, 2021, at the The Theater at Virgin Hotels in Las Vegas.

[34] Stevenson knocked down Nakathila with a check hook in the fourth round of their fight, en route to a shutout unanimous decision victory to win the vacant WBO interim junior lightweight title.

[35][36] The bout attracted criticism from pundits and analysts, citing the low number of punches thrown by Stevenson leading to a lack of action.

[30] In September 2021, it was announced that Stevenson would challenge Jamel Herring (23-2, 11 KOs) for the full WBO junior lightweight champion on October 23 at the State Farm Arena in Atlanta, Georgia.

So, it doesn’t mean much to me.”[43] In a one-sided performance that saw Stevenson use remarkable hand speed, he became a two-division world champion when he defeated Herring via tenth-round technical knockout after being ahead on all three judges' scorecards.

3 days later, the fight was confirmed for April 30 at the MGM Grand Garden Arena, Paradise, Nevada and officially announced on February 17.

[57] Stevenson's first championship defense as a unified super featherweight titlist was scheduled against the one-time WBC title challenger Robson Conceição.

[60] Stevenson missed weight by 1.6 lbs at the official weigh-ins leading to him being stripped of his WBC, WBO, and Ring titles.

In the final seconds of the fourth round, a left hand from Stevenson to the body dropped Conceição for an 8-count from referee Fields as the bell sounded.

[69] As Cruz refused to enter into negotiations,[70] the WBC ordered William Zepeda to face Stevenson instead, as the next highest ranked contender.

[71] Zepeda likewise passed on the fight,[72] as did the former unified lightweight champion George Kambosos Jr.[73] The order was finally accepted by Shuichiro Yoshino on January 11, 2023.

Stevenson dominated the fight with his speed, accuracy and ring IQ, dropping Yoshino twice and landing at will until the referee intervened.

[80][81] On August 26, 2023, the WBC ordered Frank Martin to face the former two-weight world champion Stevenson for the vacant lightweight title.

[87][88] In a very uninspiring fight with practically no action for 12 rounds, Stevenson walked away with a unanimous decision victory, with scores of 115–113, 116–112, and 116–112 and became a three-weight world champion.

[89] The fight set a CompuBox record for the least amount of punches thrown in a twelve-round contest, with neither fighter landing a double digit number of strikes in any of the rounds.

[94] Stevenson made his first defense of his WBC lightweight title against Artem Harutyunyan at Prudential Center in Newark, New Jersey on July 6, 2024.

[95] The fight would mark the Stevenson's last bout under Top Rank as his contract was due to expire, having turned pro with them a year after the Olympics.

After talks with Oscar De La Hoya and Floyd Mayweather Jr., in August 2024, he signed a promotional deal with Eddie Hearn's Matchroom Boxing.

Bring on [WBC lightweight mandatory challenger] William Zepeda at the top of 2025 and I'm ready for anyone who is brave enough to step in the ring with me.

We will be unstoppable in and out of the ring, and I will continue to show my dominance for many years to come in the sport of boxing.” Stevenson was scheduled to make the second defense of his title against Joe Cordina at Kingdom Arena in Riyadh, Saudi Arabia, on 12 October 2024.

[108] Undefeated lightweight contender Floyd Schofield (12 KOs) then made himself available and took to social media to plead to his promoter Oscar De La Hoya to make the fight.

[113] Speaking at the Ring Magazine awards ceremony on January 11, 2025, Stevenson stated he knew what it felt like being in Schofield's position being young and hungry for a world title and wanting to win.

[122][123][124][125] According to a police report, Stevenson and fellow boxer David Grayton were involved in an altercation in a South Beach parking garage.