Mateusz Gamrot was born in southern Poland. At the age of fourteen Gamrot moved to a boarding school Milicz to begin training freestyle wrestling. Gamrot has lived and trained in Poznan, Poland since he turned twenty. He divides his time between Poznan (where he lives with his wife and children) and American Top Team in Coconut Creek, Florida.

Gamrot is an accomplished grappler. He has won junior and youth medals as part of the Polish national wrestling team, is a black belt in Brazilian jiu-jitsu, and the 2014 and 2019 ADCC Submission Wrestling European Champion at 77 kg. He is also a two-time European Amateur MMA Championships at 70 kg and a two-time gold medalist at the Polish grappling championships.  

Gamrot made his professional mma debut in 2012 and went 3-0 before making his KSW debut at KSW 23 in 2013. Gamrot was the KSW Lightweight Champion from 2016 to 2020 and also the promotion's Featherweight champion after beating Kleber Koike Erbst at KSW 46. Gamrot left KSW with a record of 14-0, four title defenses, and a Knockout of the Night win at KSW 30. 

Gamrot made his UFC debut at UFC Fight Night: Ortega vs. The Korean Zombie on October 18, 2020. He and Guram Kutateladze engaged in a back-and-forth clash that won Fight of the Night honors. Kutateladze got the nod by split decision but told Daniel Cormier

 in the post-fight interview that he believed Gamrot should have been declared the rightful winner.

Gamrot finished his next three opponents, earning Performance of the Night honors for his KO of Scott Hotlzmann (UFC on ABC: Vettori vs. Holland) and his kimura submission of Jeremy "Lil Heathen" Stephens (UFC on ESPN: Makhachev vs. Moisés). Gamrot then defeated Arman Tsarukyan by unanimous decision during the Fight Night main event on June 25, 2022. This was another back-and-forth, Fight of the Night performance ending in a controversial decision. Tsarukyan dominated the striking exchanges while Gamrot got the better of the grappling exchanges, with Tsarukyan's coach telling him before the fifth round to avoid wrestling with Gamrot. Gamrot's next fight would be against Lightweight veteran Beneil Darriush at UFC 280. Gamrot was unable to find the same grappling success against Darriush as he had with his previous opponents and was outstruck in the second and third rounds. He lost to Darriush via unanimous decision.

The most entertaining moment of Gamrot's career came outside of the Octagon. During an interview with Hejt Park host Maciej Turski, Gamrot put Turski in a standing guillotine choke to demonstrate his favorite submission.