Archbishop Mark O’Toole was born in London on 22nd June 1963.   The youngest son of Marcus and Maura O’Toole who originally hail from the Irish-speaking community of Connemara, Galway, Ireland. He attended St Ignatius Primary School, Stamford Hill and St Thomas More Secondary School in Wood Green, leaving school in 1981 with four ‘A’ level qualifications. Three years later he graduated the University of Leicester with a BSc in Geography.

Following university, Archbishop Mark O’Toole entered into priestly formation at Allen Hall Seminary, London. He graduated with a BD in Sacred Theology from the University of London (Heythrop College) in 1989.

From 1989-1990 the then Deacon Mark O’Toole spent his time working at St Joan of Arc Parish, Highbury. He was then ordained to the Sacred Priesthood on 9th June 1990 by Cardinal Basil Hume.

1990-1992 Fr. Mark O’Toole entered further studies completing an M.Phil in Theology at the University of Oxford. His thesis studied the relationship between Divine and Human freedom supervised by the then Lady Margaret Professor, Dr Rowan Williams.

Following his graduation, Fr. Mark worked as an assistant priest in St Mary Magdalene parish, Willesden Green; whilst also working as a part-time lecturer in Catechesis. He joined the staff at Allen Hall Seminary full time from 1997-2002 as a lecturer in Theology and as a Formation Adviser to the seminarians.  He also served as Dean of Studies until 2002.  During this period he obtained a Sacred License in Theology from the Pontifical University, Leuven in 2000.

In 2002, Cardinal Cormac Murphy-O’Connor named Fr. Mark O’Toole as his Private Secretary.  he continued in the role until 2008 when he as appointed Rector of Allen Hall Seminary.

On 28th January 2014 he was ordained ninth Bishop of Plymouth.  During his time in Plymouth he was appointed an Honorary Canon at both Truro and Exeter cathedrals.