Johnny Herford graduated with distinction from the Royal Academy of Music Opera department in 2012, and the next year won the Song Prize at the Kathleen Ferrier Competition, and later the Jean Meikle Duo Prize alongside pianist William Vann at the Wigmore Hall International Song Competition. In 2018 he was awarded Associate of the Royal Academy of Music.

In 2015, Johnny was chosen by Philip Glass to create the role of Josef K in his opera, The Trial. The opera was premiered at the Royal Opera House Linbury Theatre, in a collaboration between Music Theatre Wales and the Royal Opera House. In recognition of his performance, Johnny was nominated for the Welsh Theatre Award for Best Male Performance in an Opera in 2015. He has also performed the role of Josef K for Theater Magdeburg, both in Magdeburg and Craiova, Romania. He returned to Music Theatre Wales in 2016 for Peter Eötvös' The Golden Dragon. 

Last year he appeared at Opera di Roma as the Novice's Friend in Deborah Warner's award-winning production of Billy Budd, and in 2017 made his debut at English National Opera in Mike Leigh's production of The Pirates of Penzance. Other recent performances have included Pascal Dusapin's Passion with the London Sinfonietta and Music Theatre Wales, his debut with Opera North in Will Todd's Songs of Love and Battle, The Traveller in Britten's Curlew River (Opéra de Dijon), Kuligin in Janacek's Katya Kabanova (Opéra de Dijon), Emireno in Handel's Ottone (English Touring Opera), a tour of operatic highlights with Scottish Opera, and Nikitch in Mussorgsky's Boris Godunov with the Philharmonia Orchestra. Forthcoming engagements include Bernard Herrmann's Wuthering Heights at the Opéra National de Lorraine in Nancy and Philip Venables' Denis and Katya for Opera Philadelphia.
Johnny recently made his solo debut at the Wigmore Hall in a programme of Ravel, Schumann and Judith Weir, accompanied by James Baillieu. Elsewhere, he has performed with Joe Middleton in the Leeds Lieder Festival, with William Vann at Julius Drake's Machynlleth Festival and at the Oxford Lieder Festival, and with Gary Matthewman for Lied in London. 

The last few years have seen the release of various recordings, including The Trial by Philip Glass, a Ralph Vaughan Williams disc titled"Purer than Pearl", a Fauré recording with the Orchestra of St John's, and recordings of contemporary English songs for Navona Records and Divine Art Recordings.
On the concert platform he appears as a soloist in music from Monteverdi to the present day, including Bach Passions and B-Minor Mass, Haydn Seasons, Mendelssohn Elijah, Brahms German Requiem, Mahler Rückert-Lieder, and Vaughan Williams Five Mystical Songs.