Iowa Highway 23 is a state highway that is signed from north to south, although it is generally a southeast to northwest alignment, in south central Iowa. It has a length of 15.92 miles (25.62 km).

Iowa Highway 23 begins at Iowa Highway 92 in the eastern portion of Oskaloosa. It goes southeast through University Park and continues southeast through Cedar. It turns east at Cedar and goes through Fremont. It then turns south to go towards Ottumwa, but ends at its intersection with Iowa Highway 149.

There have been 4 versions of Iowa Highway 23. The first lasted from 1920 to 1926 and went from the South Dakota border west of Sioux City to Fort Dodge. The second lasted from 1926 to January 1, 1969 and was a highway that went south from Milton to the Missouri border. The third version of Iowa Highway 23 lasted from January 1, 1969 until July 16, 1997 and went from Eddyville to Ottumwa. This version was replaced by U.S. Highway 63.

The current version of Iowa Highway 23 was created July 16, 1997 and was formerly the route for U.S. Highway 63.