[1] Route 12 originally began operations on 10 August 1947, and runs between Xinzhaqiao (present day Datong Road) and Tilanqiao.

[1] In 1950, route 12 was extended westward to Hengfengqiao (present day No.2 Shimen Road).

The full route, which runs between Zhongshan Park metro station and Tilanqiao, used conventional diesel buses due to the lack of overhead wires along Changning Road, which was part of the extended sector.

[1][3] On 24 June 2014, the previous mixed fleet was replaced entirely by newly-purchased Youngman trolleybuses for both the partial and full routes.

[2] In August 2021, the government of Shanghai announced that six existing trolleybus lines, including route 13, would be converted to run on conventional electric buses instead.