Pritchard was born in 1948 in Salford, Manchester. He was educated at Arnold School in Blackpool, before going on to read Law at St Peter's College, Oxford. He went on to obtain a Certificate in Pastoral Theology at Ridley Hall, Cambridge, being ordained as a priest in 1972. From 1972 to 1976, he served as a curate at St Martin's, Birmingham, and from 1976 to 1980, he was Youth Chaplain and Assistant Director of Education in the Diocese of Bath and Wells. In 1980 he became Priest in Charge of Wilton, Taunton, then from 1988 he was Director of Pastoral Studies at Cranmer Hall, Durham, and then, from 1993, Warden there. In 1996, he became Archdeacon and Canon Residentiary of Canterbury Cathedral, and in 2002 was consecrated suffragan Bishop of Jarrow.
On 11 December 2006, after a longer-than-usual selection process, it was announced that he would be the 42nd Bishop of Oxford. Having taken office at his confirmation-of-election in London on 23 March 2007, he began his work in his diocese on 8 June 2007 after a service of inauguration at his Cathedral in Oxford. In 2008, he supported Oxford Muslims' application to broadcast the adhan from the minaret of a mosque , for which he has received hostile comment and letters of complaint from local evangelicals.
Pritchard is married and has two daughters.
From 1996 to 2002, during Pritchard's time at Canterbury Cathedral, he was also a Canon Residentiary. This would have meant he was called the Revd Canon John Pritchard; however, as he was also an archdeacon, he used the style of such.