On June 13, 2016, Daivari was announced as a competitor in the WWE Cruiserweight Classic. On June 23, 2016, Daivari was eliminated from the tournament in his first round match by Ho Ho Lun. On the October 10, 2016 episode of Raw, Daivari made his main roster debut as part of the cruiserweight division on Raw, losing by submission to Cruiserweight Champion T.J. Perkins. On the Hell in a Cell pre-show, Daivari teamed with Tony Nese and Drew Gulak in a losing effort to Cedric Alexander, Lince Dorado and Sin Cara. On the Survivor Series pre-show, Daivari, Nese and Gulak were defeated by TJ Perkins, Rich Swann and Noam Dar. He then started a feud with Gentleman Jack Gallagher, which ended in an "I Forfeit" match, which he lost.
Daivari began his championship pursuits for the Cruiserweight Championship in July 2017. Akira Tozawa called Daivari out on the July 24 episode of Raw for a rematch after Titus O'Neil forfeited their singles match the week prior on Tozawa's behalf. While Neville showed up to confront Tozawa, Daivari then appeared to attack both Tozawa and Neville. He faced off against Neville the next night on 205 Live, winning via count-out. When Enzo Amore became the Cruiserweight Champion, Daivari appeared to support Amore on 205 Live and became a member of Amore's heel faction "The Zo Train", along with Tony Nese, Drew Gulak, and Noam Dar. On January 23, 2018, Enzo Amore was fired from WWE, thus forcing Amore to vacate the Cruiserweight Championship and quietly disbanding "The Zo Train". Following this, Daivari participated in a tournament to crown a new Cruiserweight Champion, but lost in the first round to the debuting Buddy Murphy on the February 6, 2018 episode of 205 Live.
During WWE Greatest Royal Rumble, Ariya teamed up with his brother Shawn Daivari and insulted four Saudi Arabian prospects before being driven out. After an extended break from action to recover from an unspecified injury, Daivari returned on the November 28 episode of 205 Live, joining Hideo Itami in an attack on a local competitor. After that, he began accompanying Itami to the ring for his matches and interfering on his behalf. On January 29 episode of 205 Live, Daivari turned on Itami after the latter lost to Akira Tozawa, the same day that Itami requested his release from WWE. On the March 23 episode of 205 Live, Daivari defeated Cedric Alexander, following a distraction from Oney Lorcan. On the April 23 episode of 205 Live, Daivari defeated Lorcan to become the number one contender for the Cruiserweight Championship. However, at Money in the Bank, he failed to capture the Cruiserweight Championship. Shortly afterwards, he would feud with Oney Lorcan, which lead to a Anything Goes match, in which he was defeated to end their feud.
In October 2019, he would begin a feud with Isaiah "Swerve" Scott, but never defeated him. Around this time, he would start wearing white pants and a Gucci belt to the ring. In 2020, he would form an alliance with Tony Nese. Over the next months leading into 2021, they would mostly be defeated by the likes of Curt Stallion and August Grey. On June 25, 2021, Daivari was released from his WWE contract.
In April 2022, Daivari was rehired by WWE as a producer. On the May 30 episode of Raw, Daivari was seen helping to break up the brawl between Cody Rhodes and Seth Rollins.