Roberts was educated at Colwyn Bay County School, Ruthin School, Trinity College, Carmarthen and Oxford University, where he won a blue in 1968. He played at Colwyn Bay, Birkenhead Park and London Welsh, captaining the latter in 1975/6.

He also represented London Counties against Fiji in 1970 before making his test debut in 1971 against England. In the same year he was selected to tour with the British Lions after having won the Grand Slam with Wales that season, and played in 11 of the provincial games while in Australian and New Zealand. Roberts switched from prop and lock on the tour and this, combined with a minor injury, never allowed him to contend for a Test place.

He played 15 times in a Welsh jersey and scored a try against England in his final international.