Israel Adesanya was born in Nigeria, but was relocated to New Zealand by his family while still an adolescent. He has a background in Muay Thai and Kickboxing, originally competing in Kickboxing and Boxing before becoming a professional Mixed Martial Artist. He amassed a 32-0 record as an amateur Kickboxer, then achieving 75-5 while a professional, with 48 KO's in his Kickboxing career. His career in boxing was far shorter, having a record of 5-1, with 1 knockout. He has also been awarded a purple belt in Brazilian Jiu-Jitsu by André Gavão.

Adesanya had one amateur MMA fight in 2009 against Neroni Savaiinaea, of which he lost by decision. However, he made the choice to return to MMA, this time as a professional in 2012. He went on an 11-fight winning streak from then on, with all wins coming by way of (T)KO, getting a win over UFC veteran Melvin Guillard in the process.

He was signed by the UFC in 2017, making his UFC debut at UFC 221 on February 21st, 2018 against Rob Wilkinson. He won the fight via TKO in the second round, collecting along the way a Performance of the Night bonus. His next fight was against Marvin Vettori at UFC on FOX 29 on April 14th, 2018. He won the close fight via split decision. He fought for the third time in the year at The Ultimate Fighter 27 Season Finale on July 6th, 2018 against Brad Tavares. He won the one-sided bout via unanimous decision, winning his second Performance of the Night Bonus along the way. He capped off his year with a first round TKO over Derek Brunson at UFC 230 on November 3rd, 2018, winning his third Performance of the Night bonus in the process. Israel Adesanya then went on to face former UFC Middleweight Champion and one of the greatest of all time, Anderson Silva in the main event of UFC 234 on February 9th, 2019.  The main event was supposed to be Robert Whittaker vs. Kelvin Gastelum for the Middleweight belt, with the co-main event set as a number one contender's fight. However, the main event was cancelled hours prior to the event due to the Champion, Robert Whittaker suffering an abdominal hernia. Adesanya's fight with Silva was rebooked to main event status. Adesanya beat the former titleholder by Unanimous Decision, winning his first ever Fight of the Night bonus as well.

Adesanya fought against Kelvin Gastelum for the Interim UFC Middleweight Championship belt in the co-main event of UFC 236 on April 13th, 2019. In a fight of the year contender, Adesanya defeated Kelvin Gastelum to become the UFC Middle Weight Interim champion, setting up a showdown to unify his interim belt, with the undisputed champion Robert Whittaker.

The most attended event in UFC history went down in Melbourne Australia October 6th, 2019 at the Marvel Arena. At UFC 243 Israel "The Last Stylebender" Adesanya fought and won against Robert "The Reaper" Whitaker via K.O. in the second round. 

Even before the fight Adesanya displayed his calm but show orientated style dancing with 3 childhood friends before getting into the octagon. In the fight Adesanya made short work of Whittaker, finishing him in the second round by knockout, after nearly knocking him out at the end of the first. This win earned him his fourth performance of the night award. 

Adesanya would then look to seek his first title defense against then undefeated prospect Paulo "The Eraser" Costa. Due to injuries that sidelined Costa, Adesanya would end up fighting Cuban wrestling standout, and three time title challenger Yoel "The Solider of God" Romero at UFC 248 on March 7th, 2020. In a fairly uneventful and low activity filled fight, Adesanya would pick up the unanimous decision victory. 

In his next title defense, Adesanya would go on to face Paulo Costa at UFC 253 on September 26th, 2020, on Fight Island. It would be a matchup of two undefeated fighters. Adesanya would pick Costa apart, knocking him out in the second round. This would earn him his fifth performance of the night bonus. 

Adesanya would go on to announce his plans to challenge Light Heavyweight champion Jan Blachowicz in his attempt at becoming only the fifth simultaneous two division champion in UFC history. The fight would take place on March 6th, 2021 at UFC 259. Blachowicz would go on to avoid Adesanya's lethal striking and would control him on the ground earning him a unanimous decision. This would be Israel Adesanya's first professional MMA loss.