Patrick McCarthy was born in the Markets area of Belfast. After leaving school he worked in an abattoir on Stewart Street. He later established his own construction business.

McCarthy was interned without trial in 1971. Following his release in 1972, McCarthy helped to set up the Lower Ormeau Community Residents Association.

McCarthy was first elected to Belfast City Council in 2001, representing the Social Democratic and Labour Party (SDLP). He served on Council until 2014.

McCarthy's father was in the merchant navy and served during the Second World War. During McCarthy's term as Lord Mayor, he led commemorations for the 90th anniversary of the Somme.

McCarthy was awarded an MBE for services to local government and community cohesion in 2015.