Gary Howlett joined Brighton & Hove Albion in 1982 from Coventry City. The highlight of his Brighton career came in the 1983 FA Cup final against Manchester United, where he crossed for Gordon Smith to head the first goal in a match that ended 2–2.
He won one cap for the Republic of Ireland against China in 1984. Gary, whose playing career was hampered by injuries, later joined AFC Bournemouth (1984–88) and York City (1988–91), and played on loan for Aldershot (1987) and Chester City (1987–88).
Gary later returned to Ireland to play for Shelbourne, making his League of Ireland debut on 1 March 1991.