Stillman Valley is a village in Marion Township, Ogle County, Illinois, United States. It lies east of Byron, south of Rockford and west of Davis Junction. The population was 1,120 at the 2010 census, up from 1,048 in 2000. The village is located on the Iowa, Chicago and Eastern Railroad, on the old Chicago Great Western Railway before it merged and was pulled up. Also, Illinois Route 72 runs through the village. It is near the site of the first battle of the Black Hawk War of 1832. The war memorial for the Battle of Stillman's Run is located in this village.