In retirement he was subject to investigation over his handling of child sexual abuse allegations and was asked to step back from ministry because of his mishandling of deviant clergy.

Speaking out against the regime of President Idi Amin, he was briefly imprisoned before fleeing in 1974 to the United Kingdom, where he devoted himself to Anglicanism, beginning his study of theology at Selwyn College, Cambridge, in 1976 and eventually gaining a doctorate in 1984.

That same year he was appointed Bishop of Birmingham where his ministry, according to the Archbishop of Canterbury, Rowan Williams, was praised by "Christians of all backgrounds".

[13] He was formally elected by the chapter of York Minster on 21 July,[14] legally confirmed as archbishop at St Mary-le-Bow, London on 5 October,[15] and enthroned at York Minster on 30 November 2005 (the feast of Saint Andrew), at a ceremony with African singing and dancing and contemporary music, with Sentamu himself playing African drums during the service.

[16][17] As Archbishop of York, Sentamu sat in the House of Lords[18] and was admitted, as a matter of course, to the Privy Council of the United Kingdom.

[16][13] For a week in August 2006, Sentamu camped in York Minster, forgoing food in solidarity with those affected by the Middle East conflict, especially the children and other civilians killed and injured during the 2006 Lebanon War, when cluster bombs were used by Israeli forces.

[27] On 19 July 2007 he was presented with an honorary degree (Doctor of Letters) from the University of Sheffield in recognition of his distinguished career as a scholar and theologian.

In his acceptance speech he praised the welcome he had received from the people of Yorkshire and made reference to the "African-Yorkshire DNA connection", joking that perhaps his parents had this in mind when they gave him the name "Mugabi", which, spelled backwards, is "Ibagum" ("ee-by-gum", a stock phrase popularly supposed to be used to express shock or disbelief in northern England).

[citation needed] Sentamu moved with his wife to Berwick and, on 14 June 2021, was licensed an honorary assistant bishop of the Diocese of Newcastle.

[33] In May 2023, he was asked to step back from active ministry by the Bishop of Newcastle after an independent review found he failed to act on a sexual abuse disclosure.

In an early TV appearance in 1988 he joined, among others, Ray Honeyford, Ann Dummett and Lurline Champagnie to discuss "Race and the classroom" on After Dark.

[38] In 2006, Sentamu featured prominently in the British press because of his comments on the treatment of detainees in Guantanamo Bay Naval Base.

[41]In the run up to the 2017 United Kingdom general election, Justin Welby, the Archbishop of Canterbury, and John Sentamu campaigned over the need to address poverty, education, housing and health.

"[42] In 2000, Sentamu, then Bishop of Stepney, was stopped by a City of London Police officer near St Paul's Cathedral.

On 9 December 2007, during a live television interview with Andrew Marr on BBC One, Sentamu made a protest against Zimbabwean president Robert Mugabe.

Sentamu took the white insert off his clerical shirt and cut it up stating that: as an Anglican, this is what I wear to identify myself that I'm a clergyman.

[46] On 26 November 2017, Sentamu returned to The Andrew Marr Show and kept his promise to reinstate his dog collar following Robert Mugabe's resignation earlier in the week.

He told the BBC that the proposed law "tends to confuse all of homosexual relationships with what you call aggravated stuff and that's the problem", but that the Anglican Communion was committed to recognising that gay people were valued by God.

"[52] In 2016, speaking to Piers Morgan, Sentamu said that he would not call homosexuality a 'sin' and still supported civil unions while opposing same-sex marriage.

[54] In 2017, Sentamu spoke out in favour of a motion at General Synod to call for the government to ban the use of conversion therapy, a controversial practice meant to change a person's sexual orientation.

[55] At the same session of General Synod, Sentamu supported a motion to offer "welcome and affirmation" for transgender persons as members of the Church of England.

But what is important, actually, is not to simply look at the past because they are going to be standing in the Abbey taking these wonderful vows: 'for better for worse; for richer for poorer; in sickness and in health; till death us do part.

'"[57] In a speech to the House of Lords on 19 November 2007, he opposed elements of the Human Fertilisation and Embryology Bill for seeking to remove a child's "need for a father" in the IVF process.

He said: "We are now faced with a Bill which is seeking to formalise the situation where the need for the ultimate male role model – that of the father – is removed in entirety.

[60] In September 2007, Sentamu wrote in his column that the parents of the missing Madeleine McCann, were subject to a "whispering campaign" and were entitled to the presumption of innocence.

[61] On Easter Sunday 2008, Sentamu baptised 20 people by full immersion in a tank of water outside St Michael-le-Belfrey Church in York.

Sentamu was named in The Guardian[66] and the Church Times[67] alongside Peter Burrows, Steven Croft, Martyn Snow, Glyn Webster and Roy Williamson, as subject of Clergy Disciplinary Measure complaints owing to their inaction on the survivor's disclosure.

[73]Matt Ineson, the victim and survivor at the heart of the case, has called for the resignations of Archbishop Sentamu and Bishop Steven Croft.