The Monona County Courthouse, located in Onawa, Iowa, United States, was built in 1892.

It was listed on the National Register of Historic Places in 1981 as a part of the County Courthouses in Iowa Thematic Resource.

The citizens of the town raised $12,500 for a courthouse in order to retain the county seat.

The main entrance is located within a wide arch portico with stone trim on the south elevation.

Decorative metal panels are located in the gable ends and wall dormers.