Anti-Trump protesters burn an effigy of the new US President
More than 1,000 protesters held up placards outside the US Embassy in London and cheered as speakers from campaign group Stand Up To Racism vowed to unite against Mr Trump 'shoulder to shoulder'.
The crowd chanted: 'Hey, ho, sexist Trump has got to go.'
Among those present was singer Lily Allen who has been an outspoken activist for left-wing causes.
Protesters take the to streets of Manchester
Mum and daughter Alice, 50 and Georgina Yelland, 14, from Kingston, Surrey, said they were worried about someone with no political experience running the White House.
Alice said: "I just fail to believe that somebody like Donald Trump is in power with no political experience.
"It's not a good idea, we wanted Bernie Sanders to win."
Mum Alice said: "He says racist and sexist things, he was voted in because there is a lot of poverty in America and someone like Trump appeals directly to their concerns.
"He appeals to people's darker sides."
The retired nurse added: "I'm also worried about climate change and nuclear weapons. He has an unhealthy relationship with the Middle East and Russia."
Anti-Trump protestors take to Tower Bridge, London, to vent their anger over inauguration
In Manchester a crowd of around 500 people gathered and chanted anti-Trump slogans and waved banners.
Stand Up To Racism campaigners burned and effigy of the new Commander-in-Chief during protests in Bristol.
Earlier, a banner reading "Build Bridges Not Walls" was draped across London's Tower Bridge today in an open show of defiance against Mr Trump's inauguration.
There were also similar demonstrations on Tower Bridge, London Bridge, Southwark Bridge, Millenium Bridge, Blackfriars Bridge, Waterloo Bridge, Westminster Bridge and Lambeth Bridge.
Cities such as Toronto to Sydney, Addis Ababa and Dublin are also protesting, with 26 bridges used for demonstrations in Spain.
The protest in London was organised by the campaign group also called 'Bridges not Walls'
We won't let the politics of hate peddled by the likes of Donald Trump take hold
Bridges Not Walls spokeswoman Nona Hurkmans said: "We won't let the politics of hate peddled by the likes of Donald Trump take hold."
Californian Katie Golden, who is in London studying a masters in screenwriting, said she was concerned about returning back home at the end of the year.
She held up a placard that said: "Dear Queen, we are sorry. Take us back? Love America."
Celebrities slamming Donald Trump
Fri, January 20, 2017
From Meryl Streep to George Clooney, here's what the celebrities have to say about President-elect Donald Trump.
1 of 13
Robert De Niro, Cher and Alec Baldwin slam Donald Trump at the We Stand United NYC Rally
The 27-year-old said: "Today is the day the wrong people became rulers for our nation.
"Trump represents everything about my country that is wrong and the Americans who voted for Trump are realising that the country we think we are part of is not the America on the world stage.
There are millions of Americans whom he does not represent, I am thinking now of Muslims, Lesbians and LGBT people.
"I am worried for myself but also for hispanics and African Americans, I'm concerned that they are no longer protected."