The Illinois Naval Militia was a naval militia created by the Illinois General Assembly in 1893, and finally dissolved in 1988. The naval militia was reauthorized by Governor Rod Blagojevich through an executive order in 2006. As a naval militia it was a state defense force and not part of the Illinois National Guard or National Guard of the United States.

A naval militia is a reserve military organization administered under the authority of a state government in the United States. It is often composed of reservists of the Navy Reserve, Marine Corps Reserve, and Coast Guard Reserve, retirees and volunteers. They are distinguishable from the U.S. Coast Guard Auxiliary which is a federally chartered civilian volunteer component of the U.S. Coast Guard and falls under the command of the Commandant of the Coast Guard through the Chief Director of the Auxiliary, and the United States Maritime Service and United States Merchant Marine, both of which are federal maritime services.