Tai Tuivasa was born in March 1993.
In 2010, Tai Tuivasa signed with the professional Sydney Roosters rugby league club but stopped playing due to a gambling addiction.
Tai Tuivasa made his professional MMA debut in August 2012 in Australia. He fought intermittently for the next four years.
In December 2012, Tai Tuivasa fought two mixed rules bouts with Combat 8 promotions. He won his fight against John Hopoate but lost to Peter Graham.
In November 2016, Tai Tuivasa signed a four-fight contract with the Ultimate Fighting Championship but was sidelined due to a knee injury and surgery.
On November 19, 2017, Tai Tuivasa made his UFC debut against Rashad Coulter at UFC Fight Night: Werdum vs. Tybura, winning by knockout in the first round. He became the first indigenous Australian to win a UFC fight and earned the Performance of the Night bonus.
On February 11, 2018, Tai Tuivasa won his fight against Cyril Asker at UFC 221 by technical knockout in the first round. On February 13, 2018, he entered the UFC's official rankings for heavyweight fighters at position 15.
Tai Tuivasa signed a new four-fight contract with the UFC in March 2018.
On June 9, 2018, Tai Tuivasa won his fight against Andrei Arlovski at UFC 225 by unanimous decision.
Tai Tuivasa lost his fight against former UFC Heavyweight Champion Junior dos Santos on December 2, 2018, at UFC Fight Night 142 by technical knockout in the second round.
Since 2018, Tai Tuivasa has celebrated his victories by drinking beer from a borrowed shoe, a practice dubbed the "shoey."
On June 8, 2019, Tai Tuivasa lost his fight against Blagoy Ivanov at UFC 238 by unanimous decision.
Tai Tuivasa lost his fight against Serghei Spivac on October 6, 2019, at UFC 243 via an arm-triangle choke in the second round.
Tai Tuivasa was scheduled to fight Jarjis Danho on June 6, 2020, at UFC 251, but the event was postponed.
On October 24, 2020, Tai Tuivasa won his fight against Stefan Struve at UFC 254 by knockout in the first round.
Tai Tuivasa was originally scheduled to fight Don'Tale Mayes on March 20, 2021, at UFC on ESPN 21, but Mayes was replaced by Harry Hunsucker. Tuivasa won the fight via a technical knockout in round one.
Tai Tuivasa won his fight against Greg Hardy on July 10, 2021, at UFC 264 via knockout in the first round, earning him the Performance of the Night award.
Tai Tuivasa was scheduled to fight Walt Harris on October 30, 2021, at UFC 267, but Harris pulled out.
Tuivasa was then scheduled to face Augusto Sakai on November 20, 2021, at UFC Fight Night 198, but the bout was scrapped because of visa issues for Tuivasa.
Tuivasa and Sakai eventually fought on December 11, 2021, at UFC 269. Tuivasa won by knockout in the second round, earning his third Performance of the Night bonus award.
Tai Tuivasa won his fight against Derrick Lewis on February 12, 2022, at UFC 271 via knockout in round two. The win earned him a Performance of the Night bonus award.
Tai Tuivasa lost his fight against Ciryl Gane on September 3, 2022, at UFC Fight Night 209 by knockout in round three despite knocking down Gane in the second round. The fight earned him the Fight of the Night award.
Tai Tuivasa lost his fight against Sergei Pavlovich on December 3, 2022, at UFC on ESPN 42 by knockout in the first round.
On September 10, 2023, Tai Tuivasa lost his fight against Alexander Volkov at UFC 293 via an ezekiel choke in the second round.
The fight was rescheduled to headline UFC Fight Night 239 on March 16, 2024.
Tai Tuivasa was scheduled to fight Marcin Tybura on February 17, 2024, at UFC 298, but the fight was rescheduled.
Tai Tuivasa lost to Marcin Tybura on March 16, 2024, at UFC Fight Night 239 in the first round due to a rear-naked choke submission.
As of May 2024, Tai Tuivasa is ranked #11 in the UFC heavyweight rankings.