Later to play for Ireland at youth and U-21 level Eamonn Collins became the youngest player to appear in a professional match in England when, in September 1980, he played for Blackpool against Kilmarnock in the Anglo-Scottish Cup aged 14 years and 323 days. He then became an apprentice at Southampton before signing professional in October 1983. He featured in three league matches for Saints before making the switch to rivals Portsmouth in May 1986.

His first spell at Exeter City began in November 1987 when he joined the club on loan, making his debut in a 2-1 home win against Stockport County. He went on to make 9 league appearances before returning to Pompey. After failing to break into the Portsmouth first team on a regular basis, he signed for Colchester United in May 1989 and added two goals in 39 league starts.

He returned to Exeter on a free transfer in July 1992, but only made 11 league outings for the club during his one season stay, moving on to Farnborough Town in December 1992. Eamonn then joined Minehead, followed by Crediton United, before switching to Elmore in February 1994. He remained at Elmore, latterly as player-manager, until December 1996 through an often-controversial period during which the Tiverton club finished runners-up in the Western League.

In 1999 Eamonn joined Dublin club St Patrick's Athletic as assistant manager to Pat Dolan, succeeding him as manager in February 2003. However, despite a League of Ireland Cup win and an FAI Cup final appearance, Eamonn quit St Patrick's in May 2004. He then joined rivals Shelbourne as assistant to Pat Fenlon in May 2004 but was to leave following Fenlon's resignation in December 2006.

Soon after leaving Shelbourne Eamonn became a player's agent and rather later through Pro10 Sports Management, one of his companies, he became the Irish authorised ticket reseller for the Rio Olympics. In August 2016 Brazilian authorities issued arrest warrants for Eamonn and two other men as part of an investigation into alleged ticket touting. Pro10 denied any wrongdoing and little more was heard of Eamonn's involvement before the case was dropped in 2017.