Walnutport is a borough in Northampton County, Pennsylvania. It was first incorporated in 1909. The population of Walnutport was 1,918 at the 2022 census. Walnutport is located along the Lehigh River and is part of the Lehigh Valley metropolitan area, which had a population of 861,899 and was the 68th-most populous metropolitan area in the U.S. as of the 2020 census. The ZIP Code is 18088.