 Corbett boxed for Ireland as an amateur before turning professional in December 1994, winning his first fight at the G-Mex Leisure Centre, Manchester, England, in which he knocked out Donaster's David Jules on a card that included Eamonn Loughran and Chris Eubank.Corbett won his first title belt, the vacant Irish cruiserweight title, in November 1996 with 5th round knockout win over Dubliner Ray Kane at the Ulster Hall in Belfast, Northern Ireland.After successfully defending that title against Nigel Rafferty and Noel Magee, Corbett added the Commonwealth cruiserweight championship to his resume with a win over the then-undefeated Chris Okoh.