Attorney Henri Brandman says he has been instructed by Blake Fielder-Civil "to commence divorce proceedings on the grounds of Amy's adultery."
Winehouse and Fielder-Civil married in Miami in May 2007, but he was arrested six months later and jailed over an assault. He was released into a drug rehab center in November but sent back to prison weeks later for breaching his bail conditions.
Winehouse shot to stardom with the multi-Grammy-winning album "Back to Black" in 2006. But her music has been overshadowed by reports of drug use, run-ins with the law and her tempestuous marriage.
Winehouse's spokesman did not immediately return a call seeking comment.
