United States gubernatorial elections were held on November 6, 2018, in 36 states and three territories. These elections formed part of the 2018 United States elections. Other coinciding elections were the 2018 United States Senate elections and the 2018 United States House of Representatives elections.

Many of the states holding gubernatorial elections have term limits which made some multi-term governors ineligible for re-election. Two Democratic governors were term-limited while six incumbent Democratic governors were eligible for re-election. Among Republican governors, twelve were term-limited while eleven could seek re-election. One independent governor was eligible for re-election.

Elections were held in 26 of the 33 states with Republican governors, nine of the 16 states with Democratic governors, one state (Alaska) with an independent governor, two territories (Guam and Northern Mariana Islands) with Republican governors, one territory (U.S. Virgin Islands) with an independent governor, and the District of Columbia with a Democratic mayor. Incumbent state governors running to be reelected included 14 Republicans, five Democrats, and one independent. Territorial incumbents running included one Republican and one independent. The incumbent Democratic mayor of Washington, D.C. also ran for re-election.

Democrats gained control of nine state and territorial governorships that had previously been held by Republicans and an independent. They picked up Republican-held open seats in the states of Kansas, Maine, Michigan, Nevada, and New Mexico, in addition to defeating Republican incumbents in Illinois and Wisconsin and not losing any seats of their own. Additionally, they won the Republican-controlled territory of Guam and the independent-controlled territory of the U.S. Virgin Islands. Republicans won the governorship of Alaska previously held by an independent. Democrats also won the total popular vote for the year's gubernatorial elections for the second year in a row.

As of 2025, this is the last time that Republicans won governorships in Arizona, Maryland, and Massachusetts, and the last time that Democrats won the gubernatorial office in Nevada.

Six women won election for the first time as Governor in 2018.

Several sites and individuals publish predictions of competitive seats. These predictions look at factors such as the strength of the incumbent (if the incumbent is running for re-election), the strength of the candidates, and the partisan leanings of the state (reflected in part by the state's Cook Partisan Voting Index rating). The predictions assign ratings to each seat, with the rating indicating the predicted advantage that a party has in winning that seat. Most election predictors use "tossup" to indicate that neither party has an advantage, "lean" to indicate that one party has a slight advantage, "likely" or "favored" to indicate that one party has a significant but not insurmountable advantage and "safe" or "solid" to indicate that one party has a near-certain chance of victory. Some predictions also include a "tilt" rating that indicates that one party has an advantage that is not quite as strong as the "lean" rating would indicate (except Fox News, where "likely" is the highest rating given). Governors whose names are in parentheses are not contesting the election.

^ Highest rating given