A surge of support for the Green Party has seen historic wins for the group in London as the Labour vote collapsed.
Reform UK made also made history with a landslide win in Havering, taking 39 seats to secure its first London council.
Labour lost control of 10 councils including Waltham Forest and Hackney, where voters elected the Green Party into their local authorities for the first time in its history. The Green Party also saw its first two borough mayors elected - Zoë Garbett in Hackney and former Labour councillor Liam Shrivastava in Lewisham.
Mayor of London Sir Sadiq Khan said the outcome was "bitterly disappointing" and the result of "far-reaching disillusionment" in Labour.
A hemorrhage of Labour votes has left Newham, Barnet, Southwark, Brent, Enfield and Wandsworth councils under no overall control by any party.
Haringey - also under no overall control - was one seat short of being taken by the Green Party, with the Greens taking 28 wards and Labour losing 30.
Among the biggest upsets was Hackney, where Labour lost 41 seats.
Westminster returned to Conservative control after the only single Labour term in its history.
Labour retained Ealing, Barking & Dagenham, Greenwich, Islington, Hammersmith & Fulham, Camden and Hounslow councils, despite making losses in each where the Green Party made gains.
Sir Sadiq said many people who voted Labour in the last general election felt "angry, disappointed and let down".
"We're still waiting for the full picture, but there's no doubt that these election results are bitterly disappointing for Labour in London.
"These results speak to a far-reaching disillusionment and fracturing in our politics, which cannot be downplayed, spun or dismissed.
"Labour has lost votes in London to a variety of different parties, but the biggest change has been Labour voters switching to the Greens," the mayor added.
The Green Party's Zoë Garbett took 47% of the vote to become one of the party's first ever borough mayors.
In a speech following her election victory, she said she believed people across London and the country were "desperate for an alternative to this failing Labour government".
She added: "Today we start the fight back.
"In this election, over and over, people kept telling me that they felt let down.
"Council services are failing those who need them most, and people are struggling to make ends meet.
"To everyone who voted for me, I truly thank you for putting your trust in me today."
Celebrating in Hackney, Green Party leader Zack Polanski said: "Years ago, Hackney would have been a Labour stronghold," Polanski said. "Zoe didn't just win by a little bit. Labour was so decisively rejected."
In Waltham Forest, the Green Party took 32 seats - having previously held none - with Labour losing 33 seats.
Richard Olszewski, the Labour leader of Camden Council, also lost his seat to the Green Party.
Reform UK's victory in Havering saw it take 39 of the 55 councillors, with the Conservatives being totally wiped out, losing all 14 wards it previously held.
Speaking after Reform secured control of Havering, Farage said: "What's happened is a truly historic shift in British politics."
"We've been so used to thinking about politics in terms of left and right, yet what Reform are able to do is to win in areas that have always been Conservative, but equally, we're proving in a big way that we could win in areas that Labour has dominated since the end of World War One."
Reform UK made gains in a number of councils including Hillingdon, Sutton, Bexley and Barking & Dagenham.
The Liberal Democrats kept control of Sutton, Richmond-upon-Thames and Kingston-upon-Thames, but failed to take target borough Merton from Labour.
The Conservatives made large gains in Wandsworth and retained Hillingdon, Harrow Bromley and Kensington & Chelsea remained under Conservative control.
The Conservative mayor Jason Perry has remained in office, as has Aspire Party's Luftur Rahman in Tower Hamlets, while Newham elected another Labour mayor in Forhad Hussain, after previous mayor Rokhsana Fiaz stood down.
Several councils are still to declare their results.