Jeremy Corbyn will join thousands of protesters on the streets of London on Tuesday as Donald Trump's state visit continues.
The Labour leader will attend and speak at the demonstration on the day the US president meets Theresa May for talks.
Mr Corbyn said the protest was "an opportunity to stand in solidarity with those he's attacked in America, around the world and in our own country".
The Labour leader's attendance at the rally follows his decision to boycott Monday night's state banquet.
It also comes after the US president attacked Labour Mayor of London Sadiq Khan on Twitter on Monday morning.
As the US President landed he fired off two tweets, spelling the London Mayor's name "Kahn" in one and in another writing: "@SadiqKhan, who by all accounts has done a terrible job as Mayor of London, has been foolishly "nasty" to the visiting President of the United States, by far the most important ally of the United Kingdom.
"He is a stone cold loser who should focus on crime in London, not me."
Mr Corbyn has accused Mr Trump of an "entirely unacceptable interference in our country's democracy" after his eve-of-visit endorsement of Boris Johnson and praise for Nigel Farage.
The Brexit Party leader described Mr Trump as “a true friend to Britain”.
The president used a Sunday Times interview to say he would have "to know" Mr Corbyn before authorising the sharing of highly sensitive US intelligence with a future Labour administration.
He also urged the Labour leader to "get along with the United States" if he wanted Britain to continue to benefit from US military and intelligence support.