Fatu made his WWE debut on the June 21 episode of SmackDown as a member of The Bloodline stable, assisting Solo Sikoa by taking out Randy Orton, Kevin Owens, and Undisputed WWE Champion Cody Rhodes. At Money in the Bank on July 6, Fatu made his in-ring debut in a six-man tag team match alongside Sikoa and Tama Tonga, defeating Rhodes, Orton and Owens. In the main event of the August 2 episode of SmackDown, the night before SummerSlam, Fatu and Tama Tonga defeated DIY (Johnny Gargano and Tommaso Ciampa) to win the WWE Tag Team Championships, marking Fatu's first title win in WWE. The following night at SummerSlam, Fatu attempted to help Sikoa and threw Rhodes onto the announcer's table, before landing a frog splash from the turnbuckle, seemingly injuring himself and Rhodes in the process. Sikoa ended up losing the match after interference from the returning Roman Reigns. On the August 16 episode of SmackDown, Fatu returned and assisted Solo Sikoa and Tama Tonga in attacking Roman Reigns and subsequently delivering a triple powerbomb through the announce table. The following week on SmackDown, Sikoa had Fatu relinquish one half of the Tag Team Titles to Tanga Loa so that Fatu could be Sikoa's personal enforcer. At Bad Blood on October 5, Fatu and Sikoa lost to Reigns and Rhodes after interference from a returning Jimmy Uso, marking his first loss in WWE. At Crown Jewel on November 2, Fatu, Tonga and Sikoa defeated the original incarnation of The Bloodline (Reigns and The Usos) in a six-man tag team match, with Sikoa pinning Reigns. At Survivor Series: WarGames on November 30, Fatu, along with The Bloodline and Bronson Reed, lost to Reigns, The Usos, Sami Zayn and CM Punk in a WarGames match.
After Sikoa lost the "Tribal Chief" title and the Ula Fala back to Roman Reigns on the Raw premiere on Netflix, Fatu began a feud with Braun Strowman, which started a month prior beginning with the January 17, 2025 episode of SmackDown. At Saturday Night's Main Event on January 25, 2025, Fatu was defeated by Strowman via a disqualification after he shoved an referee. Fatu made his Royal Rumble debut in the 2025 Royal Rumble on February 1, eliminating four contestants before getting eliminated by Braun Strowman, intensifying their feud. On the February 14 episode of SmackDown, Fatu faced Strowman and Damian Priest in a triple threat Elimination Chamber qualifying match, which was won by Priest. After weeks of matches involving the two, Fatu defeated Strowman in a Last Man Standing match on the April 4 episode of SmackDown to end their feud and face LA Knight for the WWE United States Championship at WrestleMania 41. At the event, Fatu defeated Knight to win the title, marking his first singles championship in WWE. On May 10 at Backlash, Fatu retained his title against Knight, Damian Priest and Drew McIntyre in a fatal four-way match with assistance from a debuting JC Mateo.
On June 7 at Money in the Bank, Fatu betrayed Sikoa after attacking him in the namesake ladder match, leaving The Bloodline and turning face for the first time in his career. At Night of Champions on June 28, Fatu lost the title to Sikoa after interference from Mateo and the debuting Hikuleo, ending his reign at 70 days and suffering his first pinfall loss in his WWE career. On August 3, during night two of SummerSlam, Fatu failed to regain the title from Sikoa in a steel cage match. On the October 17 episode of SmackDown, Fatu was originally scheduled to face Drew McIntyre in a number one contender's match to face Undisputed WWE Champion Cody Rhodes, however Fatu was mysteriously attacked backstage and was medically unable to compete. Fatu returned on the January 9, 2026 episode of SmackDown, where he attacked both Rhodes and McIntyre during their Undisputed WWE Championship steel cage match, which allowed McIntyre to escape the cage and win the title due to Fatu and Rhodes being distracted with each other.