Glory

Van Roosmalen was drawn against Tim Thomas in the quarter-finals of the Glory 3: Rome - 2012 Middleweight Slam Final 8 on 3 November 2012, in Rome, Italy,^[4] and won by TKO in the second round when he battered the Englishman into a referee stoppage. In the semis, he dropped Sanny Dahlbeck in each of the first two rounds before finishing him with a punch to the body in the third. Advancing to the final, he went up against Giorgio Petrosyan. His aggressive style played into Petrosyan's hands, however, and he was outclassed by the silky Italian to a unanimous decision loss.^[5][6]

Van Roosmalen took a dominant unanimous decision over Yuichiro Nagashima at Glory 4: Tokyo - 2012 Heavyweight Grand Slam in Saitama, Japan on 31 December 2012, dropping "Jienotsu" in round one and scoring with low kicks and hard punches throughout.^[7][8] He dropped Murthel Groenhart in round one en route to a unanimous decision win at Glory 7: Milan in Milan, Italy on 20 April 2013.^{[9][10][11][12]} He beat Shemsi Beqiri by unanimous decision in a back-and-forth fight at Glory 10: Los Angeles - Middleweight World Championship Tournament in Ontario, California, United States, on 28 September 2013.^{[13][14][15][16]}

Van Roosmalen rematched Davit Kiria in the semi-finals of the Glory 12: New York - Lightweight World Championship Tournament in New York City, New York, US on 23 November 2013, winning a unanimous decision.^[17][18] In the final, he was battered by Andy Ristie, getting dropped in round one before being knocked out in two.^{[19][20][21][22]} He defeated Marat Grigorian via split decision in the co-main event of Glory 15: Istanbul in Istanbul, Turkey on 12 April 2014.^[23][24][25]

Final Fight Championship

In February 2016, van Roosmalen made his professional mixed martial arts debut for Final Fight Championship. He made his debut against Theo Michailidis at FFC 22, and he won the fight via second round knockout. His next bout came on 11 March 2017 at FFC 28 against Risto Dimitrov, and he was victorious via first round technical knockout. On 13 December 2018, Van Roosmalen announced that he would transitioning from kickboxing to MMA full-time.^[31]

Bellator MMA

On 28 May 2019, Bellator MMA president Scott Coker announced via Twitter that he signed Van Roosmalen to a multi-fight contract. Van Roosmalen was expected to make his promotional debut in a featherweight bout against Cris Lencioni at Bellator 232 on 26 October 2019.^[32][33] However, Van Roosmalen missed the featherweight limit by nine pounds and the bout was cancelled, with the athletic commission stating Van Roosmalen must compete at Lightweight from now on.^[34]