The governor of Illinois is the head of government of Illinois, and the various agencies and departments over which the officer has jurisdiction, as prescribed in the state constitution. It is a directly elected position, votes being cast by popular suffrage of residents of the state. The governor is responsible for enacting laws passed by the Illinois General Assembly. Illinois is one of 13 states that does not have a gubernatorial term-limit along with Connecticut, Idaho, Iowa, Massachusetts, Minnesota, New York, Texas, Utah, Washington, Wisconsin, District of Columbia, Vermont, New Hampshire and Puerto Rico. The governor is commander-in-chief of the state's land, air and sea forces when they are in state service.

The Illinois General Assembly is the legislature of the U.S. state of Illinois. It has two chambers, the Illinois House of Representatives and the Illinois Senate. The General Assembly was created by the first state constitution adopted in 1818. As of 2023, the current General Assembly is the 103rd; the term of an assembly lasts two years.