Chai Chidchob, speaker of the lower house, in announcing the results, said Samak "can continue his premiership".
Chai said 162 of the 442 attending legislators voted against the prime minister, who fended off criticisms despite weeks of street protests calling for the government to resign.
But the results come as no surprise because Samak's six-party coalition led by his People's Power party commands a healthy majority in the Thai parliament's lower house.
The house will also vote on seven other cabinet members later on Friday.
Critics have blamed Samak for Cambodia's move to apply for a Unesco listing of a temple that sits on the border with Thailand, an ancient ruin which many Thais still claim as theirs although it was awarded to Cambodia by the International Court of Justice in 1962.
Opponents also accused him of being a proxy to Thaksin Shinawatra, the former prime minister who was ousted in a military coup in late 2006.
He has denied all the allegations.
The Bangkok-based People's Alliance for Democracy has staged weeks of street protests to press the government to resign.
The number of protesters has dwindled from the tens of thousands weeks earlier, but Samak's critics say they will not be satisfied until the entire government steps down.