Ervine is released from prison in 1980 and takes up full-time politics several years later. He stands in local council elections as a Progressive Unionist Party (PUP) candidate in 1985 Northern Ireland local elections. In 1996 he is elected to the Northern Ireland Forum from the regional list, having been an unsuccessful candidate in the Belfast East constituency. In 1998, he is elected to the Northern Ireland Assembly to represent Belfast East and is re-elected in 2003. He is also a member of Belfast City Council from 1997.