Career
Early career
In the summer of 2007 he made his first team debut for Bolton in their pre-season defeat to Hibernian. Leaving for Cyprus
After leaving Bolton in the summer of 2008, he was offered contracts at a number of English clubs including Doncaster Rovers and Luton Town, but Cassidy turned down these offers to accept a contract at Cypriot First Division club Enosis Neon Paralimni. after being impressed with the set up there. in the Cypriot First Division with Enosis Neon Paralimni. He was Ireland"s first ever footballing export to Cyprus.
He made his debut for the Cypriot club on 29 August 2009, in his side"s 3–0 defeat to Apollon Limassol, coming on as a second-half substitute.
After one year with Enosi Neon Paralimniou he left the club having made a total of 17 appearances scoring no goals. After leaving Enosis, Cassidy moved to one of the biggest clubs of the island of Cyprus, AEL Limassol.
Cassidy signed a five-year contract with the club on 9 June 2010. He made his debut, coming on as a 70th-minute substitute in their 2–1 defeat to AEK Larnaca.
But after just the one appearance, he left the club for Othellos, serving just one year with of his five-year contract.
Return to England
On 10 August 2012, he returned to England and signed for Conference National newcomers Hyde. He made his debut for the club in their 2–1 home defeat to Luton Town on 17 August 2012. He left before the end of the season.
He has represented the Republic of Ireland at U17, U18 and U19 youth levels.
In 2006 and 2007, Cassidy played in multiple games during Ireland"s qualification tournament for the 2006 Union of European Football Associations under-19 Championships.