Jim McNeil was the youngest child of a Scots-Irish working-class family, and he was educated at several Catholic schools. At fourteen he ran away from home and quickly entered the 'knockabout' world of the Melbourne waterfront. During the next six years, he worked in a variety of jobs and joined the merchant navy for a brief period.
McNeil turned to play writing in 1970 while he was serving a seventeen-year sentence in Parramatta Gaol. Attempting to bridge the communication gap between prisoners and the outside world, he became involved with a self-help rehabilitation group which performed The Chocolate Frog and The Old Familiar Juice for small audiences of visitors.
Following the public attention given to his work, Jim McNeil was released from prison in 1974 and received a year's grant from the Literature Board of the Australia Council. In 1975 he married the actress Robin Nevin but divorced after two years. His last play, Jack, had its premiere at the Nimrod Theatre in 1979.
Jim McNeil died at St Vincent's Hospital, Sydney, from the effects of alcohol poisoning. He was buried at Rookwood Cemetery in Sydney.