Ifor Owen Thomas was born on 10 April 1892 at Bay View, Red Wharf Bay, Anglesey, the only son of Owen Thomas and Isabella (née Morris), herself a celebrated singer from Dyffryn Nantlle. The family moved to Pandy, near Pentraeth, where the young Ifor was educated at the village board school before being apprenticed to a carpenter. It was his mother, alongside the Bangor singing teacher E. D. Lloyd, who first trained his voice.
His talent won him a scholarship to the Royal College of Music in 1914, chosen from a field of some 400 applicants. In 1917 he left London to continue his training on the continent, studying with the great Polish tenor Jean de Reszke in Paris and with Beniamino Gigli in Milan. He went on to build a career as an operatic tenor, later settling permanently in New York, where he became one of the most prominent figures in the city's Welsh expatriate community — Cymricising his own middle name to "Owain" and hosting scores of fellow Welsh emigrants in his home.
In New York, Thomas conducted the Côr Merched Cymru (Welsh Ladies' Choir) from 1944 onwards and, in 1945, founded the Cymric Society of New York to keep Welsh culture and language alive among the diaspora. He returned to Wales for a visit in his final year, and died in New York on his birthday, 10 April 1956, at the age of 64. He is buried at Forest Lawn Cemetery, Delawanna, New Jersey.