Williams was born in North London to a Welsh father and a Jamaican mother. He attended Christ Church Cathedral School in Oxford and Haberdashers' Aske's Boys' School, a public school in Hertfordshire. He was a choral scholar at Magdalen College, Oxford, and then became a music teacher. At the age of 28, he resumed music studies at the Guildhall School of Music in London. At Guildhall, he made his operatic debut as Tarquinius in Benjamin Britten's The Rape of Lucretia.
Williams first appeared at The Proms in 1996, as the Royal Herald in Verdi's Don Carlos. He was a soloist at the 2013 Proms production of Ralph Vaughan Williams' "A Sea Symphony", and again in 2014 Last Night of the Proms, which included performances of his own arrangements of two songs. His commercial recordings include albums for Naxos and for Signum. In 2006, Williams and the Sacconi Quartet made the premiere recording of Gerald Finzi's 1921-22 song cycle By Footpath and Stile.
Williams is the president of Junior Saint James Singers, the president of Malvern Concert Club since July 2014 and the president of the Three Choirs Festival Society since December 2016. He was appointed Officer of the Order of the British Empire (OBE) in the 2017 Birthday Honours for services to music. In 2019, he was announced as Patron for Birmingham Bach Choir.
Williams was commissioned by the Financial Times in 2014 to compose a Christmas carol. 'Christmas Bells', with words by Henry Longfellow, was premiered by the Godwine Choir at St George the Martyr church in Southwark, London.
- Hannah Nepil (22 November 2013). "Interview with baritone Roderick Williams before Albert Herring at the Barbican". Financial Times. Retrieved 12 July 2017.
- Team, i (30 May 2016). "'I count the ethnic minorities in the audience… It doesn't take long.' Roderick Williams on opera's diversity problem". inews.co.uk.
- "Facing the music: Roderick Williams". The Guardian. 16 January 2017. Retrieved 12 July 2017.
- "Vaughan Williams: A Sea Symphony (BBC Proms 2013 - Sakari Oramo: Conducts)". Retrieved 5 January 2019.
- Imogen Tilden (10 September 2014). "Roderick Williams on the Last Night of the Proms: 'Maybe I should dress as Britannia and wave a Jamaican flag'". The Guardian. Retrieved 12 July 2017.
- Andrew Clements (6 May 2005). "Finzi: I Said to Love; Let Us Garlands Bring; Before and After Summer: Williams/ Burnside". The Guardian. Retrieved 12 July 2017.
- Andrew Clements (4 November 2005). "Vaughan Williams: Songs of Travel; The House of Life; Four Poems by Fredegond Shove, Williams/ Burnside". The Guardian. Retrieved 12 July 2017.
- Andrew Clements (16 July 2015). "Venables: Song of the Severn, Pine Boughs CD review – convincing and yearning". The Guardian. Retrieved 12 July 2017.
- Clements, Andrew (14 July 2006). "Finzi: Earth and Air and Rain; by Footpath and Stile; To a Poet, Williams/ Burnside/ Sacconi Quartet". The Guardian. Retrieved 25 December 2019.
- "Roderick Williams to be President of Three Choirs Festival Society" (Press release). Three Choirs Festival Society. December 2016. Retrieved 12 July 2017.
- "No. 61962". The London Gazette (Supplement). 17 June 2017. p. B14.
- Unknown (3 April 2019). "'Roderick Williams OBE announced as new Patron of Birmingham Bach Choir.' Choir continue centenary celebrations with special recital and new appointment". What's On (Birmingham). Retrieved 4 April 2019.
- Claudia Pritchard (30 May 2016). "'I count the ethnic minorities in the audience...It doesn't take long.' Roderick Williams on opera's diversity problem". iNews. Retrieved 12 July 2017.
- Roderick Williams (14 October 2016). "How to be good? Getting to grips with Billy Budd". The Guardian. Retrieved 13 July 2017.