If granted by Government, the change would mean Cornwall joins Wales and Scotland in allowing 16 year-olds to vote in local elections.
Liberal Democrat group leader Malcolm Brown had put a motion to the council last year calling for the council to back his call to lower the voting age.
The proposal went to full council yesterday (July 7) and was approved by the council, despite opposition among Conservative councillors.
Cllr Brown said the climate change demonstrations held at County Hall and the involvement of young people in the Black Lives Matter demonstrations showed that young people care about issues and want to have their say.
Cllr Jim McKenna supported the recommendation saying that it would affect 7,500 young people in Cornwall.
He highlighted the case of Greta Thunberg who was at school when she started her climate change protests which were then replicated all over the world.
Conservative councillor James Mustoe said he would not be supporting the calls, saying the debate was “wasting time” and would only result in the council sending a letter to the Government “that will then be ignored”.
He said that lowering the voting age was a Lib Dem manifesto promise and suggested that, as Cornwall had elected Conservative MPs since 2015, it “shows that the people of Cornwall do not support lowering the age of voting”.
Pat Rogerson said she was surprised by Cllr Mustoe’s suggestion that letters sent by local councils to the Government are ignored.
She said that young people were residents of Cornwall and should be listened to.
She added: “We believe in them, we trust them and we value them. It is their future they must be part of it.”
Cllr Brown responded after the debate saying that he did not want to make it a party political issue.
He said: “Trust them (young people), trust their parents who have brought them up, trust the schools and colleges that have educated them.
“We are Cornwall Council, we speak for Cornwall, if we don’t who will?”
When put to the vote the recommendation that the council lobby the Government with a view to lowering the voting age to 16 for next May’s elections was approved with 54 votes in favour, 50 against and three abstentions.By Richard Whitehouse, local democracy reporter