After training and competing in judo for 22 years and earning his black belt, Alhassan transitioned to mixed martial arts. He made his professional debut in 2013, winning via TKO in just 25 seconds. Alhassan then compiled an overall record of 6–0 before being signed by the UFC.
Alhassan made his promotional debut at against Charlie Ward on November 19, 2016. He won via knockout 53 seconds into the first round and was awarded a Performance of the Night bonus. Alhassan then lost a split decision to Omari Akhmedov at on May 28, 2017. Alhassan faced Sabah Homasi on December 2, 2017, at UFC 218, winning by TKO in the first round; some felt referee Herb Dean had stopped the fight prematurely. Due to the controversial stoppage in the first fight, a rematch with Homasi was held on January 20, 2018, at UFC 220. Alhassan indisputably knocked him out in the first round. The win earned him the Performance of the Night bonus Alhassan was expected to face Muslim Salikhov on April 14, 2018, at UFC on Fox 29. He was replaced by Ricky Rainey due to injury. Alhassan knocked outNiko Price in 43 seconds on September 8, 2018, at UFC 228. Alhassan faced Mounir Lazzez on July 16, 2020 at. At the weigh-ins, Alhassan weighed in at 174 pounds, 3 pounds over the welterweight non-title fight limit. He was fined 20% of his purse which went to his opponent Lazzez and the bout proceeded at catchweight. He lost the fight via unanimous decision. This fight was named Fight of the Night bonus; however, Alhassan was disqualified for bonus due to missing weight, as a result a third Performance of the Night bonus was awarded and Lazzez took home an extra $50,000 from the fight.
Personal life
Alhassan and his wife have a son and a daughter.
Indictment and acquittal
Alhassan was indicted on September 24, 2018, in Tarrant County, Texas, on charges related to the alleged rapes of two women in one night in March 2018. He intended to plead not guilty. The trial was held on March 5, 2020 where Alhassan was indicted on two counts of rape of incident was alleged to have taken place on March 23rd, 2018. Alhassan's lawyer argued Alhassan engaged in consensual sex with the two women and he claims the allegations of sexual assault were unfounded. The court found Alhassan not guilty on sexual assault charges.
