City Hall was filled with voices who demanded to know why more children were not let into the country when "local councils were happy to assist" more more refugees settling in.
Caroline Pidgeon, who proposed the motion said: "It is deeply disappointing that the government has chosen to end its commitment to the Dubs Amendment after such a short period of time.
"Councils in London have stepped up and taken responsibility during a severe humanitarian crisis," she added.
She argued that local councils have rebutted claims by the government that they can only provide 350 places for children under the Dubs scheme.
The motion said the Mayor should ask for a new commitment to home 3,000 unaccompanied child refugees who are most "vulnerable".
Joanne McCartney, who seconded the motion, said: "It is absolutely right for the Assembly to pass this motion.
"London has a proud history of being open, taking in some of the most vulnerable children in the world, and offering them refuge and opportunity.
"To plan to help 3,000 children nationally, and take just 350, is nothing short of disgraceful.
"The government should urgently reverse the decision to turn their backs on children who are in desperate need of our help."
The motion was agreed by 19 votes for to 2 votes against.
Councils including Hammersmith and Fulham, Hounslow and Ealing have rehomed migrant children in the past six months.
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