Winthrop is a town in Kennebec County, Maine, United States. Winthrop is included in the Lewiston-Auburn, Maine metropolitan New England city and town area. The population was 6,121 at the 2020 census. Winthrop's population, however, approximately doubles during the summer months as part-year residents return to seasonal camps located on the shores of Winthrop's Lakes and Ponds. A recreational area located among lakes, the town includes the villages of Winthrop and East Winthrop, and is the center of the Winthrop Lakes Region. Winthrop is included in the Augusta, Maine Micropolitan New England City and Town Area.

Kennebec County is a county located in the South-central portion of the U.S. state of Maine. At the 2020 census, the population was 123,642. Its county seat is Augusta, the state capital. The county was established on February 20, 1799, from portions of Cumberland and Lincoln Counties. The name Kennebec comes from the Eastern Abenaki /kínipekʷ/, meaning "large body of still water, large bay."