Green Harbor is a census-designated place (CDP) in the towns of Marshfield and Duxbury, Plymouth County, Massachusetts, United States.

Activities specific to this beach area include bridge jumping, boating, and climbing the jetty.

There is an annual October Fest on Marginal Street, which features live music, food, shopping stands and entertainment.

There are local restaurants nearby, a coffee shop and a general store located on Marginal Street.

A seasonal food stand can be found at the entrance of Green Harbor Beach during summer months.