Before joining UFC, Randleman, nicknamed "The Monster," won two NCAA wrestling championships and was a three-time All-American at Ohio State.
Randleman debuted in the UFC in 1999 and won the heavyweight title in November of that year by defeating Pete Williams, but lost the title the following year to Randy Couture.
Randleman retired from fighting in 2011.
Randleman's wife, Elizabeth, and their four children said in a statement to MMAweekly.com, "With saddened hearts, the Randleman family confirms the passing of Kevin 'The Monster' Randleman. Behind the name, was a gentle soul and loyal friend whom will be missed by many who loved him beyond the cage. The Ohio State University, UFC, MMA, Sandusky, Ohio, communities share in the loss of Kevin's passing.
"Life without 'The Monster' will never be the same. The family requests respect and privacy during this difficult time. Kevin's family is grateful for the outpour of love and support."