[1] Due to Gary Johnson's results in the 2016 presidential election, the Oklahoma Libertarian Party had ballot status to run candidates in 2018.

Five Independents, led in a loosely coordinated effort by former Oklahoma Democratic Party chair Ivan Holmes, were candidates for statewide executive offices.

Republican labor commissioner Mark Costello, who was re-elected to a second term in 2014, was fatally stabbed on August 23, 2015.

[40] Attorney General Scott Pruitt's chief of staff Melissa Houston was appointed to serve for the remainder of the term, but pledged that she would not run for election in 2018.

Incumbent Republican commissioner Bob Anthony, the chairman of the commission, ran for re-election to a sixth six-year term in office.

[52] State questions are ballot propositions to proposed either a legislative measure or an amendment to the Oklahoma Constitution.

The governor, by executive proclamation, sets the election date for submission of the state questions to the people.