The line was built in 1906 as a cutoff to the Dedham Branch of the Boston and Providence Rail Road and purchased by the MBTA in 1973.
When the plans to replace the Washington Street Elevated were drawn up in the 1960s, the new rapid transit Orange Line was planned to continue past Forest Hills to Needham Heights. However, as the project was stalled over the next few decades, funding was only found to complete the replacement portion to Forest Hills in 1987. During construction (1979 to 1987), the line was closed entirely.