| Mahachai | |
| Native Name: | มหาชัย |
| Native Name Lang: | th |
| Address: | Sukhaphiban Road, Mahachai subdistrict, Mueang Samut Sakhon district |
| Borough: | Samut Sakhon province |
| Country: | Thailand |
| Operator: | State Railway of Thailand |
| Line: | Mahachai Line |
| Platforms: | 2 |
| Tracks: | 2 |
| Connections: | Mahachai–Ban Laem Ferry |
| Structure: | At-grade |
| Code: | ชั. |
| Classification: | Class 1 |
| Original: | Tachin Railway Ltd. |
| Mapframe: | yes |
Mahachai railway station is a railway station located in Mahachai subdistrict, Mueang Samut Sakhon district, Samut Sakhon province. It is a class 1 railway station and is the main railway station of Samut Sakhon. As there is no bridge connecting the two separate sections of the Maeklong Railway, passengers continuing onwards in either direction must use a ferry to cross to Ban Laem railway station on the opposite side of the Tha Chin River. Currently, 34 rail services operate at the station.[1]
The station opened on 29 December 1904 during the reign of King Chulalongkorn, as part of the Pak Khlong San–Mahachai railway operated by the Tachin Railway Ltd.[2]