He played for Brown University from 1974 to 1977. Gilligan was not drafted by any National Hockey League or WHA team. After his WHA career, Gilligan played in Austria for several seasons. He was later the head coach of Klagenfurt AC, SC Bern, and EHC Black Wings Linz. He was also the assistant coach of the UMass Minutemen from 1998 to 2004.