South Portland Bus Service was a municipally owned suburban provider of mass transportation.

Because the city of South Portland opted out of the Greater Portland Transit District,[citation needed] this community ran its own separate three-route bus service from 1983 until 2024, when it merged with the Greater Portland Metro.

Two routes serve major shopping areas and loop through major residential streets, funnelling residents locally and giving them access to downtown Portland.

In 2024, the City Council of South Portland voted unanimously to merge its municipal bus service with the regional Greater Portland METRO bus system.

METRO will maintain the same routes, and hire all the existing South Portland bus drivers if they so choose.