After several hours of debate, 211 out of 222 members of parliament voted in favour of amending Malaysia's federal constitution, allowing the changes to be introduced. No objections were recorded.
Two-thirds of the lower house's lawmakers needed to back constitutional changes in order for them to pass. The amendments will still have to be debated and passed in the country's senate before it can become law.
The overhaul was championed by the government of Prime Minister Mahathir Mohamad, about a year after it came to power by defeating a long-ruling coalition.
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Speaking in the lower house of parliament before MPs voted, Mahathir argued that young people in Malaysia were more politically aware than in the past.
"This move is so that they be given the chance, space and voice to ... design the country's democracy through elections," he told lawmakers.
The reforms will also allow 18-year-olds to stand for election.
In addition, the amendments introduced automatic voter registration, with citizens eligible to cast their ballots as soon as they turn 18. Previously, people had to apply to get their names on the electoral roll.
The automatic registration of 18-year-old citizens will also cover 21-year-old youths who have not registered as voters.
Mahathir said the matter would be given priority by the Election Commission in the implementation of automatic registration of voters.
"We are aware that among those who had attained the voting age (21 years) but had not registered previously, would also be registered automatically,” said Mahathir in winding up the debate.
In addition to lowering the voting age, the amendment also proposed lowering the minimum age requirement from 21 to 18 years for members of parliament and representatives at the State Legislative Assemblies.
Mahathir said the government welcomed the opposition bloc's proposal that youths aged 18 not only be allowed to vote but also be permitted to contest the elections.
As many as 7.8 million people would be added to the electoral roll by the year 2023 through the move, bringing the country's total number of voters to 22.7 million, said the prime minister.
Nearly 12.3 million people voted in the 2018 elections, from a total electorate of 14.9 million people.
Malaysia's population is around 32 million people.
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With the exception of Singapore - which still maintains a 21-year voting age - most people in Southeast Asia can vote when they turn 18. The voting age in Indonesia is 17.
The parliamentary vote represented a victory for Malaysia's four-party Pakatan Harapan ruling coalition, which has faced a series of setbacks, including losing several local by-elections.
Political analyst Sivamurugan Pandian from Universiti Sains Malaysia said the lower voting age did not necessarily mean that more people might vote for Mahathir's coalition.
"Young voters have become partyless. They don't show their loyalty to any party," he said.
"Voting patterns reflect that they are influenced by issues."
He said also a lower age would not guarantee a greater youth vote, and called for political education to start earlier.
Election watchdog Bersih 2.0 chairman Thomas Fann welcomed the changes and called for them to be passed without delay.
He added, however, that automatic voter registration would have to be tackled cautiously and only after studying the technical issues and its effect on the maintenance of electoral rolls and constituency sizes.