Sean Sullivan was born on September 16, 1971. At the age of 10 he started attending the Stelmar Nursery (Luxol Nursery). At the age of 15 Sean made his debut with Luxol's Senior Squad. During the amalgamtion between Luxol and Birkirkara, Sean was loaned to Hamrun Spartans.

In 1996 Sean Sullivan joined Valletta FC. He formed part of the squad that won the five cups (League, Trophy, Lowenbrau, Super 5 and Super Cup) . In season 1998-99 he joined Floriana FC on loan till the end of the season. In summer of 1999 he returned with Valletta FC and remained with the Citizens till 2006 making a total of 159 appearances. In season 2000/2001 he formed part of the squad making a clean sweep of six cups including the Premier League, FA Trophy, Centenary Cup, Lowenbrau, Super 5 and Super Cup.

In summer of 2006 Sean joined Birkirkara FC making a total of 9 appearances for the Stripes. In 2007 he changed club and joined Hamrun Spartans. He made a total of 18 appearances for the Spartans in a career spanning over two years.

During his career Sean Sullivan also formed part of the U-18 and U-21 National squads. He made his appearance in 3 matches with the National Squad. During the 2009 transfer market, Sean rejoined Valletta FC as a goalkeeper coach, he trained the Citizens' goalkeepers untill the end of season 2010.