Prayuth, 68, a retired army chief who first came to power in a coup eight years ago, has prevailed in three no confidence motions since a 2019 election saw him stay on as prime minister in what is now a crowded 17-party coalition.
Analysts say his parliamentary majority of 253 seats verses the opposition's 208 should ensure his survival, despite polls showing a decline in popularity.
Prayuth also faces challenges from 16 renegade lawmakers who earlier this year were expelled from his Palang Pracharat Party and have vowed to vote with the opposition.
Ten cabinet ministers are also subject of the censure, which runs until Friday with a no confidence vote scheduled for Saturday.
"For the past eight years in power, the prime minister has failed to solve the country's problems, failed to generate growth or improve people's wellbeing," Chonlanan Srikaew, leader of the opposition bloc, told the house.
"Instead, he has created more problems, particularly corruption."
Prayuth dismissed the allegations, arguing the government had solved many issues, including reviving tourism and providing financial measures to address pandemic hardship.
"I have to clarify since you accused me of being unsuccessful. This is completely untrue," Prayuth said.
The main opposition Pheu Thai, the most recent incarnation of a populist party that won five elections since 2001, also launched a parallel censure campaign allowing the public to vote against the government via messaging app Line.
Youth-led protest groups that emerged in July 2020 to challenge the government also planned gatherings in front of parliament on each day of the debate to pile pressure on Prayuth and his ministers.