Biddeford is a city in York County, Maine, United States. It is the principal commercial center of York County. Its population was 22,552 at the 2020 census. The twin cities of Saco and Biddeford include the resort communities of Biddeford Pool and Fortunes Rocks. The town is the site of the University of New England and the annual La Kermesse Franco-Americaine Festival. First visited by Europeans in 1616, it is the site of one of the earliest European settlements in the United States. It is home to Saint Joseph's Church, the tallest building in Maine.

York County is the southwesternmost county in the U.S. state of Maine, along the state of New Hampshire's eastern border. It is divided from Strafford County, New Hampshire, by the Salmon Falls River and the connected tidal estuary, the Piscataqua River. York County was permanently established in 1639. Several of Maine's earliest colonial settlements are found in the county, which is the state's oldest and one of the oldest in the United States. As of the 2020 census, its population was 211,972, making it Maine's second-most populous county. Its county seat is Alfred. York County is part of the Portland–South Portland, Maine Metropolitan Statistical Area.