Gareth David Lloyd was born in Bettws, Newport. His first acting role was as a robot in a junior school play. As a teenager, Gareth joined the Gwent Young People's Theatre in Abergavenny and The Dolman Youth Theatre in Newport, where he was a contemporary of the actor Matthew Woodyatt and the singer Nia Lynn. While there, he appeared in several plays, including Macbeth, The Threepenny Opera and Henry V, in which he played the title role. When former Labour Party leader Neil Kinnock saw the young David-Lloyd performing at Monmouth Castle, he sent him £250 to use towards his acting career.