The town was established in 1549 during the reign of King Maha Chakkrapat of Ayutthaya and originally was a centre for military recruitment.

Phraya Lawaek, the Khmer king, conscripted Thais from several towns including Chachoengsao to be in his work force.

Chachoengsao is sometimes referred to as "Paet Riu", a name derived from large fish locally caught in the past.

Paet Riu literally means "eight cuts" or slices which refers to the way the fish was cooked and served as a local dish in Chachoengsao.

The provincial slogan is The bountiful Bang Pakong River, the sacred Buddha image of Luangpho Sothon, Phraya Si Sunthon the scholar of Thai language, and the Pristine Ang Rue Nai Forest.