He has been a UUP Councillor on Lisburn City Council and was, until his election to the Assembly, a Party officer and spokesman for the Northern Ireland Manufacturers' Focus Group.

He stood for leader of the Ulster Unionist Party (UUP) against Tom Elliott in the contest after the UK 2010 General Election.

[8] In February 2013, having been subjected to a UUP disciplinary process for publicly opposing a proposal for a "unionist unity" candidate in an impending Parliamentary by-election, McCrea announced that he was resigning from the UUP, stating that he disagreed with the tactic of joint working with the rival Democratic Unionist Party.

Deputy leader John McCallister criticised the announcement, which he labelled "crazy" and claiming he and other members had not been properly consulted and suggested the decision was evidence of how "dysfunctional" the party had become.

The following deputy leader and sole councillor of the party, Johnny McCarthy resigned in 2015[12] In May 2014, up to nine women accused McCrea of sexual harassment.