Chancellor Rachel Reeves – who was at Sir Keir’s side on the front bench as usual – appeared close to tears.
Labour MP Carolyn Harris was also overcome by emotion as she told MPs that “every day we see his decency and his courage shine through”.
Sir Keir is due to hand over power to Andy Burnham on Monday, after the former Greater Manchester mayor is confirmed as Labour leader at a special Labour conference on Friday.
Conservative leader Kemi Badenoch refrained from attacking the outgoing PM’s record, instead praising him for his work on Ukraine and his friendship with the country’s president Volodymyr Zelensky.
But she did aim some jibes at Labour MPs and their next leader, who was absent from the session as he has been at all the PMQs sessions since he returned to Parliament last month.
Liberal Democrat leader Sir Ed Davey said Sir Keir had worked with people across the House of Commons and described him as a “true patriot”.
Watching on were several guests of the prime minister including campaigners he had met during his time in Downing Street.
He addressed some of them directly as he spoke, saying: “To all those in the gallery whose lives have been changed or improved by this Labour government, and all across the country who struggle to be seen or heard, you’re the reason I came into politics.”
Despite being forced out by his own MPs just two years after winning a landslide election victory, Sir Keir was met with cheers from the Labour benches as he arrived in the House of Commons.
As is often the case for a prime minister’s final question session, the tone was gentler and more light-hearted than usual, with plenty of jokes about England’s World Cup hopes as well as the by-election in Clacton.
However, it began on a sombre note with Sir Keir paying tribute to former MP Ann Widdecombe.
He said it was “chilling” that during his time in Parliament three serving or former MPs had been killed.
Badenoch paid tribute to the former Conservative minister as a woman of “high principle” with a “wicked sense of humour”.
