The 2010 Maryland gubernatorial election was held on November 2, 2010. The date included the election of the governor, lieutenant governor, and all members of the Maryland General Assembly. Incumbent Democratic Governor Martin O'Malley and Lieutenant Governor Anthony Brown won election to a second term in office, defeating Republican former Governor Bob Ehrlich and his running mate Mary Kane.

Ehrlich had previously lost to O'Malley in 2006. O'Malley and Brown became the first gubernatorial ticket in Maryland history to receive more than a million votes.

While Ehrlich won a clear majority of Maryland's counties, he lost in the area between Baltimore and Washington, which accounts for more than 90% of the state's population. This allowed O'Malley to win by a relatively large margin of 14.4%.

In his first term as governor of Maryland, Martin O'Malley had made accomplishments, including raising total state tax collections by 14%. In April 2009 he signed the traffic speed camera enforcement law. He had supported raising revenue to try to overcome an imminent state deficit. Through his strenuous lobbying, he also implemented on a statewide level, Maryland StateStat One, the same CitiStat system he used to manage the city of Baltimore as mayor. One off his first actions as governor was to close the Maryland House of Corrections in Jessup, a notoriously violent maximum-security prison. By 2010, O'Malley's approval ratings had reached 55%, making his chances of reelection very good.

In the Democratic primary O'Malley faced J. P. Cusick and Ralph Jaffe, placing him in an unusual position, as he had run unopposed in the 2006 Democratic primary. He benefited from being the incumbent, and he handily defeated them in the primary. O'Malley received 86.3% of the vote. Cusick came in second with 9.7%, and Jaffe finished in last place with 5% of the vote. O'Malley again chose incumbent Democratic Lieutenant Governor Anthony Brown as his running mate.

The frontrunner for the Republican primary was former Republican Governor (and O'Malley's predecessor) Bob Ehrlich. He faced Brian Murphy in the primary. Like O'Malley, Erlich had also run unopposed in the 2006 Republican primary. Ehrlich easily defeated Murphy in the Republican primary by a margin of 75.8%-24.2%. He chose his former Secretary of State Mary Kane as his running mate.

Polling for the election overwhelmingly showed O'Malley would be reelected. The first poll taken in September 2009 showed him with an 11-point lead over Ehrlich. Throughout the election, only a few polls showed Ehrlich with a lead. By the last few months of the campaign, O'Malley held a strong double-digit lead over Ehrlich. The last poll taken showed him with a 10-point lead over Ehrlich: 52%-42%.

Ehrlich was endorsed by high-profile people. These included Terrapin basketball standout and Memphis Grizzlies NBA draft pick Greivis Vásquez; and his former lieutenant governor, who was then the chairman of the Republican National Committee, Michael Steele. He was also supported by former Massachusetts governor Mitt Romney and former New York city mayor Rudy Giuliani. The support of these individuals elevated support to his campaign.