The lieutenant governor of Illinois is the second highest executive of the State of Illinois. In Illinois, the lieutenant governor and governor run on a joint ticket and are directly elected by popular vote. Gubernatorial candidates select their running mates when filing for office and appear on the primary election ballot together. When the governor of Illinois becomes unable to discharge the duties of that office, the lieutenant governor becomes acting governor. If the governor dies, resigns or is removed from office, the lieutenant governor becomes governor. Under the Illinois Constitution, the Attorney General is next in line of succession to the Governor's office after the lieutenant governor, but does not succeed to the lieutenant governor's office. From the impeachment of Rod Blagojevich in 2009, until the inauguration of Sheila Simon in 2011, Attorney General Lisa Madigan would have become governor if Pat Quinn had vacated the office. Historically, the lieutenant governor has been from either the Democratic Party or Republican Party. The current lieutenant governor is Democrat Juliana Stratton.

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.