Scores of spectators watched the racing on a 200 meter-long dirt track in the seaside province of Chonburi, some 80 km (50 miles) southeast of the capital, Bangkok.
The race, which sometimes takes place at the end of the monsoon, was paused during the coronavirus pandemic but returned last year.
Most Thai farmers no longer use water buffalo for farming but many are still keen to keep the animals.
"Today, it doesn't matter for for me if I win or lose. I wanted to preserve this tradition," said Somchai Kamchab, 58, who owns a buffalo competing in the race.
(Reporting by Vorasit Satienlerk and Panu Wongcha-um, Editing by Alexandra Hudson)
