Havering Council in east London has become the first publicly elected body in the UK to back leaving the European Union.
Councillors voted by 30 to 15 in favour of a motion declaring the UK would be better off outside the EU.
The UKIP group leader on the council Lawrence Webb described it a "fantastic result".
The sole Labour member, Keith Darvill, said it had been "wrong" to hold the vote.
UKIP leader Nigel Farage offered his congratulations to Havering councillors on their decision.
Susana Mendonca, BBC London political correspondent
Havering Council's move is significant because of the signal it sends, rather than what it can actually achieve because the views of 30 local councillors will clearly not determine the outcome of the EU referendum.
But here we have an elected body that's supposed to focus on local services, taking sides in a national debate over Britain's future in Europe.
That's a powerful symbol for UKIP - who were behind this motion - and for Tory euro sceptics to hold up as a victory for their argument on the national stage.
But scrutiny of the wording of the motion voted on reveals it claimed EU directives had "a negative impact" on "the ability and cost of Havering Council to fulfil its obligations". There is no mention of the EU funding that Havering has benefited from over the years - thought to be almost £2m since 2005.
This debate in north east London, just as in the wider national campaigns to "Leave" or "Remain" in the EU, highlights what opposing sides omit to tell us, just as much as what they do say.
The motion does not have any formal implications, but Mr Webb said he hoped it would encourage other local authorities to adopt the same stance.
An alternative motion was tabled by the East Havering Residents' Group in favour of allowing individuals to make up their own minds.
Mr Darvill, who voted for that motion, said it was "wrong to hold the vote when we haven't got the outcome of negotiations yet" but that he believed it was in the "best interests" of Britain to remain within the EU.
He accused UKIP and Conservative councillors of working to "sideline more important issues and deny residents a debate".
Records seen by the BBC appear to show council projects have been allocated over £1.9m in funding from EU projects since 2005.
But Mr Webb argued: "EU money has to be match-funded by the council - if we cut ties we'd have more say over how to spend that money."
He said: "We as local councillors have to make decisions on rules and regulations that come out of the EU. They have a direct impact on local services.
"It is important that message gets out. Hopefully other councils will be minded to have a vote and we will have a better, more honest, open debate."