Worth County is a county located in the U.S. state of Iowa. As of the 2020 census, the population was 7,443. The county seat is Northwood. The county was founded in 1851 and named for Major General William Jenkins Worth (1794–1849), an officer in both the Seminole War and the Mexican–American War.

Northwood is a city in Worth County, Iowa, United States, along the Shell Rock River. The population was 2,072 at the time of the 2020 census. It is the county seat of Worth County.