The joint sitting of the House and the Senate on Tuesday evening elected the Pheu Thai Party's Srettha Thavisin the 30th prime minister of Thailand with 482 votes for and 165 votes against him and 81 abstentions.
There are 500 elected House representatives and currently 249 appointed senators. Mr Srettha needed a simple majority of 375 votes. In the parliament, 728 were present, meeting the needed quorum.
Of the 482 votes for Mr Srettha, 330 are House representatives and 152 are senators. Of the 164 votes against him, 152 votes are representatives and 12 are senators. The 81 abstentions were 13 representatives and 68 senators.
The parliamentary session for the prime ministerial vote started late Tuesday morning. About 11am, Pheu Thai leader Cholnan Srikaew nominated Mr Srettha, a property tycoon, as prime ministerial candidate and the debate on Mr Srettha's qualifications for the job followed.
Many parliamentarians said Mr Srettha should have attended the session to introduce himself and his policies and clarify allegations made against him.
Some parliamentarians voiced concerns about accusations of tax avoidance in land purchases by property developer Sansiri Plc when Mr Srettha was still chief executive of the company.
At 2.50pm Pheu Thai leader Cholnan said his party was aware of the allegations against Mr Srettha, but its legal team had already investigated them and found no evidence proving that Mr Srettha had violated any law.
Parliament President Wan Muhamad Noor Matha ended the debate on Mr Srettha's qualifications at 3.11pm and started the voting.
The voting results were announced about 5.40pm.
Parliament President Wan will propose the prime minister-elect for royal approval.