He made his first-class debut in 1965 for the Victorian Sheffield Shield team against New South Wales scoring 62 and 5.
An elegant stroke maker and fine cover fieldsman, his highest first-class score was 202 for Victoria against South Australia in 1966.
He made his Test debut the following year against the touring Indian side, scoring 81 and 35 in Adelaide batting at number three.
He played one further season of interstate cricket, scoring 783 runs at 52.20 to help Victoria to victory in the Sheffield Shield in 1973–74.
In 1983, Sheahan suggested that the annual World Series Cup limited overs series may be fixed, stating that, "Mr Packer [the owner of the television station which broadcast the matches] has a fair hand in — or Mr Packer's organisation has a fair hand in —saying who actually plays off in the final.”[3]