MPs have voted in favour of a proposal to lower the voting age in all UK elections from 18 to 16.
A backbench motion calling for the change was passed by the Commons by 119 to 46, a majority of 73.
However, the result is not binding on the government - the Conservatives are opposed to the move.
Lib Dem Stephen Williams, who championed the debate, said cutting the voting age would be a "vital step in the renewal of Britain's democracy".
'The time has come'
The Bristol West MP claimed there was widespread support among Parliamentarians and youth charities to extend the franchise to 1.5m 16 and 17-year-olds.
The Lib Dems promised the change in their 2010 election campaign and Labour pledged in its manifesto to give MPs a free vote on the issue.
Mr Williams said: "I believe that 16 and 17-year-olds have sufficient maturity and sufficient knowledge in order to cast a vote if they want to. We don't have compulsory voting in this country so we would simply be affording the opportunity for 16 and 17-year-olds to vote if they wished."
He added: "We do not have an electoral competence test for people aged 18 and above so I do not think we should apply it to people age 16 and 17 either."
The Labour Party backed the move as an "idea whose time has come".
Shadow constitutional reform minister Wayne David said the majority of the opposition front bench supported votes at 16.
But Chloe Smith, speaking on behalf of the government said the evidence for such a change was "not clear cut".
She argued that it was more important to increase registration and turnout among young people who currently do have the vote.
Signatories to the backbench motion included Labour's Fabian Hamilton and Hugh Bayley, Conservative former minister Sir Peter Bottomley, Lib Dem Julian Huppert, the SNP's Pete Wishart and Green MP Caroline Lucas.
Ms Lucas argued that cutting the voting age could boost voter turnout.
But some MPs voiced reservations at the plans, including Conservative backbencher Philip Davis.
The Shipley MP pointed out the age at which teenagers could be sold cigarettes had now been increased to 18.
"If people aren't capable as he sees and this House sees of making the decision as to whether or not to smoke at the age of 16 when why does he think they are capable of deciding which party should be in government at the age of 16?" he said.
The Labour MP, Barry Sheerman, said he had changed his mind on extending the franchise, arguing that voting at 16 would "squeeze" childhood.
Scottish 16-year-olds are set to be allowed to vote in the referendum on independence, due in 2014.
Speaking in the Commons, the SNP's Pete Wishart said he was "astonished" so many MPs were "prickly" about the issue of giving 16 and 17-year-olds the vote.
Speaking after the debate, Stephen Williams said: "Today Parliament made history by supporting my motion to give 16 and 17 year olds the right to vote."
He said it was now time for the government to act, calling for his bill - to put the motion into law - to be given a "fair hearing".
The prime minister's official spokesman said the government has "no plans" to change the voting age".