Polk County is a county located in the U.S. state of Nebraska. As of the 2010 census, the population was 5,406. Its county seat is Osceola.
In the Nebraska license plate system, Polk County is represented by the prefix 41 (it had the forty-first-largest number of vehicles registered in the county when the license plate system was established in 1922).
Polk County was formed in 1856. It was named after President James K. Polk.