David Alderdice was born on 2 June 1966 to Rev David and Helena Alderdice. He was educated at Queen's University Belfast and Manchester College, Oxford, where he studied medicine.

Alderdice specialised in Dermatology and has worked as a Consultant Dermatologist at the Ulster Hospital since 2010. He previously worked as a Consultant at Causeway Hospital.

In 1997, Alderdice was elected to Belfast City Council (BCC), representing the Alliance Party. He served on BCC until 2005 and was subsequently elected as a councillor on North Down Council. Alderdice retired as a councillor in July 2010.