[12] At the 2012 Summer Olympics in London, England, Madsen was defeated by another Russian wrestler, Roman Vlasov, in the second round of the men's Greco-Roman 74 kg category.

[13] Because his opponent advanced further until the final round, Madsen qualified for the repechage bout, where he scored four points and defeated France's Christophe Guénot.

[14] In the bronze medal match, Madsen was unable to score enough points in the first two periods, and lost to Lithuania's Aleksandr Kazakevič, finishing in fifth place.

[20] Madsen made his promotional debut against Alexandre Bordin at Cage Warriors Academy's inaugural event on September 23, 2018.

Madsen headlined Cage Warriors Academy Denmark 2 against Mathew Bonner on December 15, 2018 and won the bout via unanimous decision.

Madsen faced Danish boxer Patrick Nielsen in an MMA bout at Olympian Fight Night 1 on June 8, 2019.

[29] After recovering from shoulder injury and staph infection, Madsen returned to face Austin Hubbard on March 7, 2020 at UFC 248.

[44] On June 17, 2024, Madsen announced that he would be launching a mixed martial arts promotion called Dominance Fighting Championship (DFC).