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."

Augusta is the capital of the U.S. state of Maine and the county seat of and most populous city in Kennebec County. Augusta is included in the Lewiston-Auburn, Maine metropolitan New England city and town area. The city's population was 18,899 at the 2020 census, making it the 12th most populous city in Maine, and 3rd least populous state capital in the United States after Montpelier, Vermont, and Pierre, South Dakota.