Samut Sakhon was formerly called Tha Chin probably because, in the old days, it had been a trading port dealing with a vast number of Chinese junks. In 1548, a town named Sakhon Buri was established at the mouth of the Tha Chin River. It was a centre for recruiting troops from various seaside towns. The name of the town was changed into "Mahachai" when Khlong (canal) Mahachai was dug in 1704 to join the Tha Chin River at the town. Later, the town was renamed Samut Sakhon by King Rama IV but it is still popularly called "Mahachai" by the villagers.

Samut Sakhon is located 30 kms. from Bangkok. The province occupies a total area of 872 square kilometres and is administratively divided into 3 districts: Muang Samut Sakhon, Krathum Baen, and Ban Phaeo. It is a major fishing port and also the biggest producer of brine salt.