Portsmouth City Council has backed leaving the European Union in June's referendum.
A majority of councillors voted in favour of a motion declaring the UK would be better off outside the EU.
John Ferret, Labour councillor, said the EU "has no bearing on the council" and talking about it was "ridiculous".
Leader of the council, Conservative Donna Jones, said: "As one of the biggest employers we have first-hand experience of the effects of the EU."
A referendum on whether Britain should remain in the European Union is to be held on Thursday 23 June.
Two motions in support of leaving the EU, one proposed by Conservative councillors and the other by UKIP councillors, were debated.
The first, from UKIP leader Colin Galloway, said: "This council agrees that Portsmouth and indeed all of Britain would be better off outside the European Union."
The other, put forward by Ms Jones, said: "This council believes that Portsmouth should vote to leave the EU in the forthcoming election."
Councillors voted 21-15 in favour on both motions.
The Conservatives are the largest party on the council but do not have majority control.
Gerald Vernon Jackson, leader of the Liberal Democrats, the second largest party, said the council "shouldn't be telling people how to vote".
Julie Swan, Ukip's deputy group leader who seconded the motion, said: "I'm delighted that the council has passed this motion.
"I wasn't born the last time that the British people were allowed to vote on membership of the EU.
"It's important to debate this once-in-a-lifetime opportunity and to encourage the people of Portsmouth to get involved."
Havering Council in east London was the first publicly elected body in the UK to back leaving the European Union, followed by Bromley.