The Mahaska County Courthouse in Oskaloosa, Iowa, United States, was built in 1886.

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

[1] In 1986 it was included as a contributing property in the Oskaloosa City Square Commercial Historic District.

The present courthouse was built in the Romanesque Revival style on part of the Oskaloosa public park.

It was altered in 1934 and it now has an Art Deco effect, giving the building a rather odd appearance.