Five-year-old Santisuk's job involves duty at a checkpoint in the Saiburi district in the Yala province and helping residents collect coconuts.
The monkey was adopted by policeman after he was found with a broken arm, and was soon trained to pick up coconuts - each service being rewarded with a bottle of milk.
The precinct's Police Corporal Yutthapol Phromdao Yutthapol takes Santisuk with him on patrol every day.
He said compared to other checkpoints, where officers had to deal with annoyed motorists, his was a 'happy place'.
Motorists willingly slowed their vehicles to play with the monkey and others got out to have their photo taken with it.
Other police precincts are considering introducing their own monkey recruits after Santisuk - which means 'peace' in Thai -proved to improve the force's image in the troubled, predominantly Muslim province.
Separatists are blamed for most of the attacks on Thailand's predominantly Muslim deep south, which often target Buddhists and Muslims associated with the Thai state, such as police, soldiers, government officials and teachers.