Boris Johnson has branded Donald Trump the "previous president" and hailed his "refreshing" conversation with successor Joe Biden.
Mr Johnson said he agreed with the US president-elect that their two countries should "once again" co-operate on various global issues.
Speaking at Prime Minister's Questions, Mr Johnson told the House of Commons: "One of the many merits of the excellent conversation I had yesterday with president-elect Joe Biden was that we were strongly agreed on the need for once again the UK and the US to stand together to stick up for our values around the world.
"To stick up for human rights and stick up for global free trade, to stick up for NATO, and to work together in the fight against climate change.
"It was refreshing, if I may say, to have that conversation and I look forward to many more."
Mr Johnson added he was "delighted" that Mr Biden and his incoming vice-president, Kamala Harris, shared "many areas" of "common cause" - including next year's climate change summit in Glasgow.
"I had and have a good relationship with the previous president - I do not resile from that," the prime minister said.
"It is the duty of all British prime ministers to have a good relationship with the White House.
"But I'm delighted to find the many areas in which the incoming Biden/Harris administration is able to make common cause with us.
"In particular, it was extremely exciting to talk to president-elect Biden about what he wants to do with the COP26 summit next year, in which the UK is leading the world in driving down carbon emissions and tackling climate change."
Speaking later during a visit to a Tesco distribution centre in southeast London, the PM said it was a "return to the kind of business we are used to doing together".
"Sticking up for democracy around the world, human rights, free trade, NATO - Joe Biden is a very strong believer in the transatlantic alliance and indeed the special relationship - and above all climate change," Mr Johnson said.
The PM held a 25-minute phone call with Mr Biden on Tuesday.
They talked about the importance of implementing Brexit in such a way that upholds the Good Friday Agreement, with the prime minister assuring the president-elect that would be the case.
The Internal Market Bill - the government's controversial Brexit legislation that ministers have admitted will allow them to break international law - was not understood to have been raised specifically in the call.
Mr Biden has previously warned against the Good Friday Agreement becoming a "casualty" of Brexit.
Downing Street on Wednesday said that Mr Johnson hadn't raised the case of Harry Dunn during the call with Mr Biden.
But the prime minister's spokesman added: "It wasn't discussed last night but sure we'll be having further discussions in the coming months.
"We continue to press for justice."