Puripol Boonson was crowned the 200m champion as he set a new SEA Games record in Hanoi on Saturday.
Puripol clocked the fastest time of 20.37sec, breaking the Games record and his own national mark of 20.58sec set at the National Games in Si Sa Ket.
Vietnam's Nghia Ngan Ngoc came second withn a time of 20.74 while another Thai sprinter Chayut Khongprasit came third on 20.77.
Parinya Chuaimaroeng gave the Kingdom a second gold in the track and field event after she won women's triple jump top honours with a leap of 13.66 metres.
The silver medal went to Vietnam's Ngoc Ha Vu Thi, who jumped 13.52 metres while Indonesia's Maria Londa Natalia came third on 13.45.
Thailand also won the 4x400m mixed relay, followed by Vietnam and the Philippines.
It was also a good day for Thailand in bodybuilding as Thailand picked up two gold medals yesterday.
Ekkaphon Sukthong, who won the world title in 2019, won the men's 80kg light-middleweight event while four-time world champion Aphichai Wandee won gold in the men's 85kg middleweight event.
Wichai Singthong, the 2015 world champion, won bronze in the men's 75 welterweight while Detnarong Prathet, the 2019 world champion, finished fifth in the 70kg lightweight event.
Elsewhere, Thailand women's volleyball team beat the Philippines 3-0 (25-15, 25-13, 25-14) in the preliminary round.
In sepak takraw, Thailand defeated hosts Vietnam 3-0 in the men's team regu, while the women's team regu team blanked Laos 3-0 with consummate ease.
Chaba Kaew's target
Despite a 1-1 draw with Myanmar in their second match on Friday night, Thai women's football team coach Miyo Okamoto is confident of wrapping up the first round hostilities as the Group B winners.
The Chaba Kaew failed to claim three points as they could not hold onto the advantage Irravadee Makris had given them in the 13th minute.
Win Theingi Tun grabbed the all-important equaliser for Myanmar in the 79th minute at the Cam Pha Stadium.
After two matches, Thailand and Myanmar have the same four points and are only separated at the top by goal difference with the Chaba Kaew holding a slight edge.
Okamoto said after the game she is hoping to claim the top spot in the pool after the final round of group matches today when the Thais take on Laos and Myanmar play Singapore.
"We started off the game well and played at a quick pace. We scored early but Myanmar were able to equalise in the second half. It's a pity that we couldn't win the match," said the Japanese coach.
She added: "We can't chose who we play in the semi-finals but we can try to put in our best effort in every match.
"Of course, we want to finish at the top of the group and face the runners-up of the other group, but we are ready to play any team in the semi-finals."