Gareth Griffith was born in Bangor in 1940 and brought up in Caernarfon. He left school at 16 and joined the police cadets in Liverpool in 1957, before enrolling at Liverpool College of Art in 1960. After some thirty years of teaching — including a two-year contract in Kingston, Jamaica, during which he maintained his own practice — he retired early and built a new studio in the garden of his home in Mynydd Llandygai, near Bangor, where he has lived for over four decades.

Working across painting, sculpture, and installation, his practice moves fluidly between two and three dimensions. His 2019 solo touring exhibition Trelar // Trailer, curated by Steffan Jones Hughes of Oriel Davies, travelled to Aberystwyth Arts Centre, Tŷ Pawb and Oriel Myrddin, offering an immersive encounter with recent work. His work is held in the collections of Amgueddfa Cymru, the Walker Art Gallery, and the Arts Council Collection. He was winner of the painting prize at the Welsh Artist of the Year 2012, joint winner of the 2022 BEEP Painting Biennial and, in 2025, received the Gold Medal for Fine Art at the 2025 National Eisteddfod of Wales.