Mwekassa began kickboxing training in 2003, but when he found not much opportunity, he switched over to boxing. In the boxing world, Mwekassa went 15-4, with all but one of his wins coming by KO/TKO. During this time, Mwekassa claimed the WBF International Cruiserweight Title and the ABU All-Africa Heavyweight Title.
After approaching GLORY about the opportunity to compete for the promotion, Mwekassa debuted at GLORY 16 in May 2014, facing MMA and kickboxing veteran Pat Barry. Mwekassa knocked out Barry with a left uppercut late in the first round in one of the biggest upsets in kickboxing.
Mwekassa lost to Saulo Cavalari in the finals of the GLORY 18 Light Heavyweight Contender Tournament, and he lost to Cavalari again at Bellator MMA & GLORY: Dynamite I in a match to determine a new champion. Mwekassa later won the interim GLORY Light Heavyweight Title at GLORY 31, defeating Mourad Bouzidi, but he lost a title unification bout to Artem Vakhitov at GLORY 35.