Derrick Lee Smith, 51, won the multimillion-dollar judgement by default in Lenawee County Circuit Court during a virtual hearing on Monday after Combs, 54, failed to show up.
A lawyer for Combs said the rapper would move to have the judgement dismissed.
"This man (Smith) is a convicted felon and sexual predator, who has been sentenced on 14 counts of sexual assault and kidnapping over the last 26 years," lawyer Marc Agnifilo said in a statement.
"His resume now includes committing a fraud on the court from prison, as Mr Combs has never heard of him, let alone been served with any lawsuit. Mr Combs looks forward to having this judgement swiftly dismissed," the statement added.
Smith, who was sentenced to prison for 75 years on sexual misconduct and kidnapping charges, filed complaints against Combs in June and August. He was given a temporary restraining order against Combs, who has several other sexual assault cases still pending.
Combs, founder of the landmark label Bad Boy Records, is one of the most influential producers and executives in hip-hop and a hugely successful performer, as well as the impresario of his own Sean John clothing line.
With AAP.