Thai tycoon Anutin Charnvirakul took office as prime minister on Sunday, after an endorsement from the king started the conservative's tenure as the nation's new leader.

"His Majesty the King has endorsed Mr Anutin Charnvirakul to be prime minister from now onwards," said secretary-general of Thailand's lower House of Parliament Arpath Sukhanunth, reading aloud a royal command in a ceremony at Anutin's Bhumjaithai Party headquarters in Bangkok.

Anutin, 58, has previously served as deputy prime minister, interior minister and health minister – but is perhaps most famous for being the architect of Thailand's 2022 cannabis decriminalisation.

He becomes the kingdom's third leader in two years, but has taken power with coalition backing conditional on dissolving parliament within four months to hold fresh elections.

"I will work at my full capacity with honesty and morality worthy of His Majesty's trust, for the benefit of the people and for the country," Anutin said immediately after taking office.

Anutin ousts the populist Shinawatra clan's Pheu Thai party, which has monopolised the top office since 2023 elections but saw their dynasty heiress Paetongtarn Shinawatra sacked as prime minister by court order last month. (AFP)