over Brazilian Rodrigo Cavalheiro Correia by technical knockout six seconds before the final bell. Gamrot earned a Knockout of the Night bonus award with the performance. At KSW 32: Road to Wembley, Mateusz defeated Marif Piraev via TKO in the second round, getting his tenth straight win to start his career. KSW Lightweight Championship On May 27, 2016 at KSW 35, he fought for the vacant KSW Lightweight Championship belt against former British BAMMA and Russian M-1 Global champion Frenchman Mansour Barnaoui. He claimed the title via unanimous decision and both fighters were awarded the Fight of the Night bonus. At KSW 36: Materla vs. Palhares on October 1, 2016, he defended his title via heel hook against Renato Gomes Gabriel in the second round. Gamrot faced former UFC fighter Norman Parke at KSW 39: Colosseum on May 27, 2017. He won the bout and retained the title via unanimous decision. Gamrot rematched Norman Parke at KSW 40: Dublin on October 22, 2017. At the weigh-ins, Parke came in one pound over the championship limit and the bout was deemed a non-title bout. After the bout was stopped due to eye pokes that left Parke unable to continue, Parke shoved Gamrot's cornerman, Borys Mankowski, which resulted in Marcin Bilman, another professional fighter who was in the champion's corner, responded by landing a punch on Parke. Gamrot was subsequently fined 30% of his purse and Bilman was handed a two-year ban from KSW events. On March 3, 2018 at KSW 42: Khalidov vs. Narkun, Gamrot defeated Grzegorz Szulakowski via keylock submission in the fourth round, defending the KSW Lightweight Championship. Two-division champion On December 1, 2018 at KSW 46: Narkun vs. Khalidov 2, he fought for a second belt, this time for the KSW Featherweight Championship, against submission specialist Kleber Koike Erbst, where he won the bout after a five-round domination, capturing the organization's second crown. Vacating the titles On May 17, 2019, in a video on Borys Mankowski's YouTube channel, Gamrot announced that he had vacated his two belts and did not renew his contract with KSW. On March 6, 2020, KSW announced Gamrot's return to the organization. The KSW double champion was scheduled to return at KSW 53 in Lodz, Poland against the Brazilian Edimilson Souza, but due to a coronavirus pandemic the event was canceled. On July 11 he fought his third bout at KSW 53: Reborn against