Prayut arrived at 9.06am, about one hour after the station opened. He was wearing a blue shirt, the colour of his United Thai Nation (UTN) Party and was escorted by his personal bodyguards.
His wife and twin daughters also cast their vote, but did not arrive with him.
Some 100 voters were spotted queuing at the polling station since 8am, and among the crowd were also members of the local and foreign press.
Prayut is UTN Party’s sole PM candidate and won a No 4 ranking in the second Nation Poll on preferred PM candidates with a score of 8.85%. The poll was published earlier this month.
Move Forward’s Pita Limjaroenrat moved to the top of the list from third place in the first survey with a score of 29.37%. Pheu Thai’s Paetongtarn Shinawatra and Srettha Thavisin came in second and third respectively with 27.55% and 13.28%.