The 2018 United States Senate election in Maryland took place on November 6, 2018, in order to elect a member of the United States Senate to represent the State of Maryland. It was held concurrently with other elections to the United States Senate, elections to the United States House of Representatives, and various state and local elections. Incumbent Democratic U.S. Senator Ben Cardin was re-elected to a third and ultimately final term by a landslide margin of almost 35 points, the largest margin in any election for this seat since Maryland began holding direct elections for Senate in 1913.

Benjamin Louis Cardin, is an American lawyer and politician serving as the senior United States senator from Maryland, a seat he has held since 2007. A member of the Democratic Party, he was the U.S. representative for Maryland's 3rd congressional district from 1987 to 2007. Cardin served in the Maryland House of Delegates from 1967 to 1987 and as its speaker from 1979 to 1987, the youngest person to ever hold the position. In his half-century career as an elected official, he has never lost an election.