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 fired a Twitter broadside at Labour Mayor of London Sadiq Khan, as soon as he arrived in the UK.
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 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.