Super Mario Land 2 takes place immediately after the original Super Mario Land. Wario has put an evil spell over Mario Land while Mario was away in Sarasaland. The inhabitants are now brainwashed into thinking that Wario is their master, and Mario is their enemy. Wario's motive behind this sudden attack was to take control over Mario's castle in order to have a palace of his own. In order to stop Wario, Mario must find the 6 Golden Coins throughout Mario Land to gain access to his castle. Mario eventually faces off against Wario inside his stolen castle and defeats him, thus reclaiming his castle.

While its predecessor was similar to the original Super Mario Bros., Super Mario Land 2 has more in common with later games: the player may now scroll the screen to the left, levels are not linear by virtue of a map screen that permits him to choose a level, and the game has battery backup saves. Hidden levels have been added too, another element unavailable in the first game. In addition, the game keeps track of how many enemies the player has killed (by jumping on them, hitting them with a fireball, etc.).

This game contains 3 minigames. In one minigame you play a game of Skill Crane which you lower a claw over a moving conveyor belt which contains items. The other minigame requires you to stop a pair of mice which will gnaw through paths to various prizes. Stopping them in the correct position will leave the path to the better items open. The third minigame is a slot machine which requires coins to play. Winning can gain you coins or even more lives.