The effects of prize fighting along with him being overweight and unhealthy after a long life of overindulging in food and alcohol took its toll on the boxer. Like most boxers of the time, he did not live a very long life. Sullivan died at age 59 at his home in Abington, Massachusetts, supposedly from heart disease. At the time of his death, Sullivan had a young boy named Willie Kelly in his custody. The priest of Sullivan’s church had brought Kelly, an orphan, to the front of the parish and encouraged anyone with the means to care for the boy to do so. Sullivan is buried in the Old Calvary Cemetery in Roslindale, a neighborhood of Boston. He died with 10 dollars in his pocket (which is equivalent to almost 180 dollars in 2018). According to the county where Sullivan died he had an estate worth $3,675.