He was right: the same upsurge of populist support he enjoyed to win the presidency was reminiscent of the way millions of working-class voters in the UK ignored the warnings of the Westminster establishment and voted for Britain to leave the EU.
It would be overdoing it to say Trump's victory had its roots in the UK's anti-elite referendum revolution of summer 2016 -- the Republican candidate had long calibrated his pitch as an anti-establishment swipe at Washington. But there were similarities between the UK referendum and the US election, particularly the powerful force of voters in both countries who have lost their jobs because of globalization -- and Trump recognized that.
There will be people in Britain today who voted to leave the EU and who will now feel vindicated by Trump's victory.
But in the long-term, what does a President Trump mean for Britain and its special relationship with the US? In recent years, that special relationship has been tough: Barack Obama made his opposite number David Cameron work hard at it, with the President making clear to Britain that it could not be taken for granted by symbolically moving a bust of Winston Churchill out of the Oval Office shortly after he entered the White House.
In the last year, that hard work had paid off: Obama threw his weight behind Cameron's campaign for Britain to stay in the EU, warning that Brexit would mean Britain would be "back of the queue" in any trade talks with the US.
Now that Trump is president-elect, that warning is no longer relevant as Britain suddenly looks set to be pushed closer to the front of the queue. Trump, who is opposed to TTIP -- the Transatlantic Trade and Investment Partnership with the EU -- has said he is interested in an independent trade deal with the UK as it finds its feet outside Europe.
Yet this post-Brexit life raft does not mean that Trump's victory is good news for Britain. Theresa May's government faces a huge diplomatic challenge with the new president. Britain is charting unpredictable waters outside Europe, with its future still undecided. Having an unpredictable president to deal with -- rather than Hillary Clinton, who had strong links to Britain's political establishment -- is going to make the special relationship incredibly hard to nurture.
Trump is more sympathetic to Russia than his Democratic opponent, a stance which will jar with Britain, whose Foreign Secretary Boris Johnson takes a hardline stance against Putin.
As world leaders continue to grapple with the problem of Syria and Russia's military presence there, it is difficult to see any common ground between the British Prime Minister and new US President.
As Cameron before her, May and her government have been frosty toward the prospect of a President Trump.
It is notable that, despite the historically close links between the British Conservatives and the Republican Party, Trump's closest UK political ally is Nigel Farage, the former leader of UKIP who helped inspire the new President's cry of "Brexit plus plus plus."
The special relationship is going to be under strain for some time to come.