Speaking at the party’s European election campaign launch in Edinburgh on Thursday, Mr Rennie said the UK’s departure from the EU will be bad “however you look at it”.
He said voters have the opportunity to put an end to the division and economic uncertainty by backing his party at the ballot box on May 23.
The Lib Dems made large gains across England and Wales in the local council elections last week, winning 703 seats.
Mr Rennie said: “People are fed up with Brexit. It has caused division in our country and damaged our economy.
“Voters now have the chance to make that stop by voting for the Liberal Democrats.
“Brexit is bad for us, however you look at it. Our economy is in jeopardy, business needs to trade without new barriers, Airbus is already leaving and farmers can’t get the seasonal workers they need.
“Our public services are under threat - hundreds of thousands of EU nationals live in Scotland. We rely on them to staff our hospitals and schools and we want them to feel welcome here.
“Finally our security is at risk. Our police need to work with European police forces. We can’t risk peace in Northern Ireland and we want to work with the whole of Europe to keep us safe from climate change.
“A vote for the Liberal Democrats is a positive vote to solve these problems, prove the UK is an outward looking country and remain in the EU.”