At a special party conference in Manchester on 24 June 2007, he formally handed over the leadership of the Labour Party to Gordon Brown, who had been Chancellor of the Exchequer under Blair's three ministries. Blair tendered his resignation on 27 June 2007 and Brown assumed office during the same afternoon. Blair resigned from his Sedgfield seat in the House of Commons in the traditional form of accepting the Stewardship of the Chiltern Hundreds, to which he was appointed by Gordon Brown in one of the latter's last acts as Chancellor of the Exchequer. The resulting Sedgefield by-election was won by Labour's candidate, Phil Wilson. Blair decided not to issue a list of Resignation Honours, making him the first Prime Minister of the modern era not to do so.
Blair had an antagonistic relationship with Zimbabwean President Robert Mugabe and allegedly planned regime change against Mugabe in the early 2000s. Zimbabwe had embarked on a program of uncompensated land redistribution from the country's white commercial farmers to the black population, a policy that disrupted agricultural production and threw Zimbabwe's economy into chaos. General Charles Guthrie, the Chief of the Defence Staff, revealed in 2007 that he and Blair had discussed the invasion of Zimbabwe. Guthrie advised against military action: "Hold hard, you'll make it worse." In 2013, South African President Thabo Mbeki said that Blair had pressured South Africa to join in a "regime change scheme, even to the point of using military force" in Zimbabwe. Mbeki refused because he felt that "Mugabe is part of the solution to this problem." However, a spokesman for Blair said that "he never asked anyone to plan or take part in any such military intervention."
On 27 June 2007, Blair officially resigned as Prime Minister after ten years in office, and he was officially confirmed as Middle East envoy for the United Nations, European Union, United States, and Russia. Blair originally indicated that he would retain his parliamentary seat after his resignation as Prime Minister came into effect; however, on being confirmed for the Middle East role he resigned from the Commons by taking up an office of profit. President George W. Bush had preliminary talks with Blair to ask him to take up the envoy role. White House sources stated that "both Israel and the Palestinians had signed up to the proposal". In May 2008 Blair announced a new plan for peace and for Palestinian rights, based heavily on the ideas of the Peace Valley plan. Blair resigned as envoy in May 2015.
In November 2007 Blair launched the Tony Blair Sports Foundation, which aims to "increase childhood participation in sports activities, especially in the North East of England, where a larger proportion of children are socially excluded, and to promote overall health and prevent childhood obesity." On 30 May 2008, Blair launched the Tony Blair Faith Foundation as a vehicle for encouraging different faiths to join together in promoting respect and understanding, as well as working to tackle poverty. Reflecting Blair's own faith but not dedicated to any particular religion, the Foundation aims to "show how faith is a powerful force for good in the modern world". "The Foundation will use its profile and resources to encourage people of faith to work together more closely to tackle global poverty and conflict," says its mission statement.
Blair made an animated cameo appearance as himself in The Simpsons episode, "The Regina Monologues" (2003). He has also appeared as himself at the end of the first episode of The Amazing Mrs Pritchard, a British television series about an unknown housewife becoming Prime Minister. On 14 March 2007, Blair appeared as a celebrity judge on Masterchef Goes Large after contestants had to prepare a three-course meal in the Downing Street kitchens for Blair and Bertie Ahern. On 16 March 2007, Blair featured in a comedy sketch with Catherine Tate, who appeared in the guise of her character Lauren Cooper from The Catherine Tate Show. The sketch was made for the BBC Red Nose Day fundraising programme of 2007. During the sketch, Blair used Lauren's catchphrase "Am I bovvered?"
When Blair resigned as Prime Minister, Robert Harris, a former Fleet Street political editor, dropped his other work to write The Ghost. The CIA-influenced British prime minister in the book is said to be a thinly disguised version of Blair. The novel was filmed as The Ghost Writer with Pierce Brosnan portraying the Blair character, Adam Lang. Stephen Mangan portrays Blair in The Hunt for Tony Blair (2011), a one-off The Comic Strip Presents... satire presented in the style of a 1950s film noir. In the film, he is wrongly implicated in the deaths of Robin Cook and John Smith and on the run from Inspector Hutton. In 2007, the scenario of a possible war crimes trial for the former British prime minister was satirised by the British broadcaster Channel 4, in a "mockumentary", The Trial of Tony Blair, with concluded with the fictional Blair being dispatched to the Hague.
In May 2007, before his resignation, it was speculated that Blair would be offered a knighthood in the Order of the Thistle, owing to his Scottish connections (rather than the Order of the Garter, which is usually offered to former Prime Ministers). Blair reportedly indicated that he did not want the traditional knighthood or peerage bestowed on former prime ministers.