Joe Anderson, Mayor of Liverpool, said closer working between cities would be of more benefit than independence, moving government from London to Edinburgh.
He spoke during a meeting with Glasgow City Council leader Gordon Matheson in Liverpool .
Mr Anderson welcomed the calls for more powers to be devolved to city level, such as the cities deal being extended to Scotland.
Council officials are still in talks with the UK government over what powers could be given to allow councils to deal with specific issues.
Mr Anderson said: "Liverpool has more in common with Glasgow than either of us does with London or Edinburgh.
"True devolution happens at the city level, where myself and Gordon can make a real difference to people's lives and build economies which give people what they need - jobs and security.
"Moving powers from London to Edinburgh doesn't help Glasgow be a better city."
He said he was backing a No vote in the referendum based on shared experiences of people across cities in Scotland and England.
He added: "I've been to Glasgow many times and feel a real affinity for the people there.
"Glasgow and Liverpool people have a similar sense of humour and a passion for standing up for justice and fairness.
"This week I've welcomed over 150 leaders from cities around the world and all of them want to be able to serve their people by having the powers to decide what's best for their own. That's why I'm supporting the No Campaign."
The City Deal means cash invested by councils is "earned back" through income tax, corporation tax, VAT and PAYE contributions.
Mr Matheson said Glasgow and Liverpool shared much history and more so than Glasgow does with some parts of Scotland.
He said: "We're kith and kin, with a similar history and the thought of Glasgow and Liverpool being in foreign countries after September is a heartbreaking prospect.
"We established the National Health Service and the welfare state together.
"And we want to stay together and co-operate closely with other sister cities in England to grow our economies and create modern vibrant cities."