She began her career with the Glyndebourne Festival Chorus, and was a regular broadcaster on the Welsh Home Service. She subsequently had a distinguished career as an opera singer. She sang Bach arias at her debut at The Proms, in 1955. She toured the Soviet Union with the English Opera Group in 1964, singing the lead in The Rape of Lucretia. She was also known for her 1969 performances as Mistress Quickly in Verdi's Falstaff with the Welsh National Opera. In 1969, her voice was described by a critic as "not particularly large, but the general purity and warmth of its tone gives it a direct, communicative power. And the singer uses it with taste and imagination."
The many recordings by Helen Watts included a "monumental" edition of forty Bach cantatas, with Helmuth Rilling conducting the Bach-Collegium Stuttgart. She also made multiple recordings as a soloist in Handel's Messiah, various roles in Wagner's Ring cycle, and an album of Welsh songs with the Treorchy male voice choir. She was asked to choose her favorite recording, book, and luxury as a guest on BBC Radio 4's Desert Island Discs in 1970. They were: Favourite track: Betrachte Meine Seele, from the St. John Passion by Johann Sebastian Bach; Book: Illustrated book on gardening; Luxury: Velasquez, The Maids of Honour, (Las Meninas) in the Prado.
- "Helen Watts obituary in the". Daily Telegraph. 1 November 2009. Retrieved 15 November 2009.
- "Helen Watts: fine contralto who enjoyed a long and varied career". Times Online. 22 October 2009. Retrieved 15 November 2009.
- Patrick O'Connor, "Helen Watts Obituary" The Guardian (15 October 2009).
- Raymond C. Ericson, "Welsh Contralto Bows as Soloist" New York Times (7 February 1969): 30.
- Helen Watts, Desert Island Discs, BBC Radio 4 (14 September 1970).
- Profile, gramophone.co.uk; accessed 12 April 2014.
- D. Brook, Singers of Today (Revised Edition - Rockliff, London 1958), pp. 198–200.
- Helen Watts profile, bach-cantatas.com; accessed 12 April 2014.