278 backed it, with none against.
But Conservatives were ordered to abstain in the vote - which is not binding.
The Treasury responded to a letter by Richmond council calling for the increase, saying it was unable to make a decision at that time.
Councillor Robin Brown says “The previous level of benefits was simply not enough”.
Boris Johnson says no decision has yet been made about the increase.
Councillor Robin Brown, Finance and Resources Lead Member of Richmond Council, said:
"Richmond Council wrote to the Chancellor of the Exchequer at the end of last year to request that the uplift of Universal Credit introduced at the start of the pandemic is made permanent.
"HM Treasury responded to the letter to say it was unable to make a decision on extending the temporary £20 uplift at this time.
"We hope that the Government acknowledges how vital this is when it votes on the matter later this evening.
"The Universal Credit uplift introduced at the start of the pandemic has helped nearly 11,000 Richmond upon Thames residents pay for everyday essentials such as food and utilities.
"The previous level of benefits was simply not enough."
