Best known for starring as Perry Smith in the 1967 film In Cold Blood and as the titular character on the TV series Baretta, he initially gained fame as a child actor in the MGM short film series Our Gang.
He began his career in his family's song and dance act as a member of The Three Little Hillbillies.
He played the role of the Mystery Man in the 1997 David Lynch film Lost Highway. In January 2021, he was the subject of a TV special about his wife Bonnie's murder, and his eventual acquittal in the case. The special is titled Murder in the Family: Robert Blake, and aired on Reelz.
He was married to Sondra Blake from 1961 to 1983 and Bonnie Lee Bakley from 2000 to 2001. He has three children, Noah, Delinah and Rosie.
He appeared alongside Robert Young in the 1939 movie Bridal Suite.