Born into a poor family, dos Santos was raised by a single mother. In order to help his family he started to work at the age of ten. His first serious contact with martial arts happened at the age of 21, when he began training in Brazilian jiu-jitsu under Yuri Carlton. After only six months of training, dos Santos won a few jiu-jitsu tournaments in Salvador. Dos Santos was soon invited to join an MMA practice, where he met his boxing coach Luiz Carlos Dórea. Roughly a year after he started training jiu-jitsu he had his debut professional fight.
Dos Santos turned professional in 2006 at the age of 22. He fought in small promotions in Brazil such as Demo Fight, Extreme Fighting Championship, Minotauro Fights and Mo Team League. He won six of his first seven bouts, suffering his only loss to Joaquim Ferreira, a fighter he had previously beaten.
Dos Santos debuted for the UFC on October 25, 2008 at UFC 90. Considered a major underdog, he knocked out top contender Fabrício Werdum at a minute and twenty seconds of the first round with a strong uppercut, earning himself a "Knockout of the Year" award.
Returning on February 21, 2009 at UFC 95 he fought promotional newcomer Stefan Struve, defeating him at fifty-four seconds of the first round by knockout.
On September 19, 2009, Dos Santos continued his winning streak and defeated Mirko Cro Cop at UFC 103. During the third round Dos Santos dominated Cro Cop in the clinch with knee strikes and punches. A knee from the clinch and a right uppercut apparently caused damage to Mirko's left eye, causing him to verbally submit.
Dos Santos was supposed to fight Gabriel Gonzaga at UFC 108. However, Gonzaga pulled out of the bout on November 25, 2009 due to a staph infection. Instead on January 2, 2010, dos Santos fought Gilbert Yvel, winning the fight via TKO at two minutes and seven seconds of the first round.
Dos Santos defeated Gabriel Gonzaga on March 21, 2010, at UFC Live: Vera vs. Jones by knockout in the first round. earning him his second "Knockout of the Night" award.
Dos Santos faced Roy Nelson on August 7, 2010, at UFC 117. The fight saw dos Santos use a variety of strikes and, for the first time, a successful takedown. Despite dos Santos' striking ability, Nelson was able to stay in the fight, resulting in the fight going to decision. Dos Santos won via unanimous decision (30-26, 30-27, 30-27). Following the win, dos Santos was expected to challenge Cain Velasquez for the heavyweight title. However, a torn rotator cuff suffered by Velasquez sidelined the champion for nearly a year.
On January 11, 2011, it was revealed that dos Santos would be one of the coaches of The Ultimate Fighter Season 13, opposite to Brock Lesnar. They were scheduled to face each other on June 11, 2011, at UFC 131, but Lesnar pulled out of the bout due to a recurrence of diverticulitis and was replaced by Shane Carwin. Dos Santos dominated Carwin and defeated him via unanimous decision (30-27, 30-27, 30-26), relying predominantly on his boxing skills, but showed more variety in his game by landing a couple of kicks and completing two takedowns in the third round.
Dos Santos faced Cain Velasquez at UFC on Fox 1 for the UFC Heavyweight Championship on November 12, 2011. He defeated Velasquez in 64 seconds of the first round via KO to win the UFC Heavyweight Championship He dropped Velasquez with an overhand right and finished him off with a series of punches. The performance also earned him his third "Knockout of the Night" award. After the fight, it was revealed that he had a torn meniscus in his knee; he subsequently underwent a successful knee surgery.
Dos Santos was scheduled to face Alistair Overeem on May 26, 2012 at the MGM Grand Garden Arena at UFC 146. On April 4, 2012, the Nevada State Athletic Commission announced Overeem had failed a pre-fight drug test. Consequently, Overeem's request for a license was denied. On April 20, 2012, Dana White the UFC president announced Frank Mir would be replacing Overeem. Dos Santos was able to keep the fight standing, showing his superior boxing skills, resulting in a KO in the second round.
A rematch against Cain Velasquez was expected on September 22, 2012 at UFC 152. However, it was later announced by Dana White that the fight would take place in Las Vegas on December 29, 2012 at UFC 155. dos Santos fell short to Velasquez after five rounds of a one-sided match and lost his title via unanimous decision (50-45, 50-43, 50-44). This marked the first time dos Santos had suffered a loss in the UFC. Dos Santos later claimed that he was training so hard prior to the bout with Velasquez that he developed rhabdomyolysis, a (sometimes fatal) breakdown of muscle fibers that releases their contents into the bloodstream and that the condition affected his performance during the fight.
Dos Santos was expected to face Alistair Overeem on May 25, 2013 at UFC 160. However, in early March, Overeem pulled out of the bout citing an injury. The bout was expected to be rescheduled for a future event, However, on March 9, UFC President Dana White confirmed that dos Santos' next opponent would be Mark Hunt at the same event. In the UFC 159 post-fight conference, Dana White indicated that if dos Santos defeated Hunt, he would be the #1 contender for the heavyweight championship. Dos Santos won the fight via third-round knockout in a bout that earned both participants Fight of the Night honors.
A third fight with Cain Velasquez took place on October 19, 2013 at UFC 166. Although dos Santos experienced more moments of success than in their second fight, he was still dominated by Velasquez for most of the fight. He lost via TKO at 3:09 of the fifth round after landing on his head during an attempted submission and follow up punches from Velasquez.
Dos Santos was expected to face Stipe Miocic on May 24, 2014 at UFC 173. However, the bout was slightly delayed and was scheduled to take place a week later on May 31, 2014 at The Ultimate Fighter Brazil 3 Finale. However, on May 5, it was announced that dos Santos pulled out of the fight citing a hand injury and he was replaced by Fabio Maldonado.
A rescheduled bout with Miocic eventually took place as the main event at UFC on Fox 13 on December 13, 2014. Dos Santos won the back-and-forth fight by unanimous decision (48-47, 49-46, 49-46). The performance earned both participants Fight of the Night honors.
After a year away from the sport, dos Santos had the three-years-delayed fight with Alistair Overeem which eventually took place on December 19, 2015 at UFC on Fox 17. He lost the bout by technical knockout in the second round.
Dos Santos faced Ben Rothwell on April 10, 2016 at UFC Fight Night 86. He won the fight by unanimous decision (50-45, 50-45, 50-45).
Dos Santos was originally expected to face Stefan Struve in a rematch on February 19, 2017 at UFC Fight Night 105. However on January 12 Struve pulled out due to a shoulder injury. Despite having over six weeks before the event, promotion officials elected to remove Dos Santos from the event instead of having him face a replacement.
Dos Santos faced Stipe Miocic on May 13, 2017 at UFC 211 for the heavyweight title. He had previously beaten Miocic by a close unanimous decision at UFC on Fox: dos Santos vs. Miocic in 2014. Dos Santos lost the fight via TKO in the first round.
Dos Santos was expected to face Francis Ngannou on September 9, 2017 at UFC 215. However, on August 18, Dos Santos was pulled from the match after being notified of a potential USADA violation.
Dos Santos states that Antônio Rodrigo "Minotauro" Nogueira is his hero.
He is a Roman Catholic.
In January 2013, he announced that he had divorced his wife of ten years before competing at UFC 155.
On March 9, 2017, Dos Santos' first child was born.Ultimate Fighting Championship
UFC Heavyweight Championship (One time)
One successful title defense
Knockout of the Night (Three times)
Fight of the Night (Two times)
Longest winning streak in UFC Heavyweight division history (9)
Second most knockout victories in UFC Heavyweight division history (8)
Upset of the Year (2008) vs. Fabrício Werdum on October 25
2014 December Fight of the Month vs. Stipe Miocic
2010 All-Violence Third Team
2011 All-Violence First Team