Ashmont is a major terminal for the MBTA bus system, with nine local routes – 18, 21, 22, 23, 24, 26, 215, 217, and 240 – serving the station busway.

[1] The first Ashmont station was a simple building along the original Shawmut Branch of the Old Colony Railroad, which opened in 1872.

[5] Like Fields Corner, Ashmont was designed for convenient transfer between rapid transit trains and surface streetcars.

From 1948 to 1968, Hudson Bus Lines operated service from Ashmont to several South Shore locations.

[7][8] The station was made nominally accessible, though the 1990 passage of the Americans with Disabilities Act created stricter standards.

The developer and the local community expressed their desires for a larger renovation, but the MBTA proceeded with design work.

[10]: 33  The Shawmut and Fields Corner projects were constructed separate from the delayed Ashmont work.

[10]: 33  The MBTA removed the membrane canopy from the design in September 2004 due to lack of funds.

[10]: 8  The $10.3 million architectural work lasted until June 14, 2011, at which point the station was declared accessible.

[10]: 34  In September 2011, a "HOLD" sign was installed on the trolley platform to allow an easier connection for those transferring from the Red Line.

[10]: 32 Buses replaced service on the Ashmont Branch and Mattapan Line from October 14–29, 2023, to allow for track work.