Tonga's 42,000 voters will elect 17 of the 26 members of parliament, with the remaining nine reserved for the kingdom's nobility.
Electoral officials said voting was "steady" and provisional results were expected late Thursday.
Previously the parliament was dominated by politicians selected by the monarch, who also picked the prime minister and cabinet.
The swing towards democracy follows riots in the capital Nuku'alofa four years ago, which claimed eight lives and destroyed much of the business centre as people protested against the slow pace of political reform.
In an address to the nation ahead of polling, the king said the election was "the greatest and most historic day for our kingdom.
"You will choose your representative to the parliament and thus the first elected government in our country's long history," he said.
After the election the newly elected representatives will select a prime minister, a process that could take days.
Tonga Holds First Vote
Comments