Officers from Region 8 Police and Chalong Police arrived at the popular temple, officially called Wat Chaithararam, at about 3:30am yesterday (Jan 26) to make the arrests.
The officers found the gamblers in three groups in front of the temple, with two of the groups playing cards and the third group playing Hi-Lo.
Seized as evidence were playing cards, dice and cash.
Most of the 18 were vendors with stalls set up as part of the annual Wat Chalong Fair, which began last Saturday (Jan 21), police noted.
Each night after the events and entertainment at the fair shut down, the gamblers assembled for entertainment of their own.
All 18 were taken to Chalong Police Station to be charged with illegal gambling, officers confirmed.
The seven-day Wat Chalong Fair and its activities will conclude tonight (Jan 27).