Paper Mario: Sticker Star is a 2012 role-playing video game developed by Intelligent Systems and published by Nintendo for the Nintendo 3DS. Following Super Paper Mario (2007), it is the fourth installment in the Paper Mario series and part of the larger Mario franchise; it is the first game in the series released on a handheld console. The story follows Mario and a new ally named Kersti as they travel across the Mushroom Kingdom to retrieve the six Royal Stickers scattered by Bowser.

Unlike previous Paper Mario games, Sticker Star uses a distinct papercraft visual style, which is heavily incorporated into its gameplay mechanics. Sticker Star introduces stickers, which are littered throughout the game world and serve as single-use items or power-ups, aiding the player in turn-based battles against enemies or in solving puzzles. Game designer and producer Shigeru Miyamoto insisted that gameplay should be distinct from previous Paper Mario games, which led to Sticker Star placing greater emphasis on gameplay and combat, with less focus on story. Allies alongside Mario were cut due to complications with sticker mechanics, and there was a large decrease in characters with unique designs.

Sticker Star was released in November 2012 in North America, and December 2012 in other regions. It received generally favorable reviews, with praise for its graphics, writing, and strategy. Criticism targeted its unbalanced difficulty in combat, lack of traditional role-playing game elements, minimal story, and abundance of identical Toads instead of the original fictional races the series had been known for. Reception for the sticker mechanics was mixed. A sequel, Paper Mario: Color Splash, which carried over many ideas introduced in Sticker Star, was released for the Wii U in October 2016.

Sticker Star features a similar visual style to its predecessors. The player controls a paper cutout version of Mario in a 3D papercraft world, with landscapes ranging from snowy areas and forests to volcanoes represented as the Mushroom Kingdom. The story focuses on Mario's efforts to retrieve the six Royal Stickers that have been scattered by Bowser after he attacked the annual Sticker Fest. Mario is accompanied by Kersti, a sticker fairy, who bestows upon Mario the power of stickers.

A major facet of Sticker Star's gameplay is the use of collectible stickers, which are used to gain abilities to progress through the game. The player collects stickers that are found and peeled off from various areas in the environment. Additionally, the player can purchase stickers using coins or receive them from non-playable characters (NPC). The player has limited inventory space, with larger stickers taking up more room. Stickers are used both in combat and for interacting with the environment. The player can enter a state called "Paperization", which will lay the screen down flat to reveal additional secrets not visible regularly. Real-world objects can be found, known in-game as "Things", such as baseball bats and scissors, that can be turned into special types of stickers called "Thing Stickers", which are often needed to solve puzzles in the overworld. For example, a Fan Thing Sticker can be placed in strategic areas in the environment and, when activated, creates wind that moves or destroys obstacles.

As in previous games, combat in Sticker Star takes place in turn-based battles which are initiated when Mario comes into contact with enemies in the overworld. The player's available attacks are determined by the stickers on hand from their inventory. For example, possession of the Jump sticker can be used to attack an enemy by jumping on it. Certain kinds of attacks are required depending on the enemy being fought; an enemy wearing a spiked helmet cannot be jumped on and must instead be attacked using a different kind of sticker, like a hammer. Thing Stickers are used to inflict more damage on enemies, and certain types of Thing Stickers are required to make boss battles easier. Each sticker is removed from play after one use, making it necessary for the player to consistently collect new stickers. The player increases their maximum health points (HP) and other stats through collection of HP-Up hearts, which give Mario five more health points and stronger attacks.

Every year, the Sticker Comet lands in the Mushroom Kingdom, and those who wish on it have a good chance of their wish being granted by the Royal Stickers that reside within the comet. Mario attends the Sticker Fest, a festival held in the city of Decalburg to celebrate the Sticker Comet's arrival; where Princess Peach presents the comet on stage. There, as the Toads all prepare their wishes, Bowser interrupts the celebration and breaks the comet into six parts, the Royal Stickers, scattering them over the Kingdom, with one falling on Bowser's head; Mario tries to stop him, but fails and is knocked unconscious. He is later awakened by Kersti, a sticker assistant, who is tasked with granting the wishes made to the Sticker Comet. After cleaning up Bowser's mess in Decalburg, Mario and Kersti depart to search for the first of the Royal Stickers.

Mario and Kersti traverse six areas to retrieve each of the six Royal Stickers. Each Royal Sticker is guarded by a boss, and upon defeating each, a cutscene shows how the boss received the Royal Sticker and what their motivation was. Megasparkle Goomba took the first Royal Sticker as a crown and calls himself a king; Tower Power Pokey was sealed by Kamek; Gooper Blooper was a music-lover uncontrollably releasing poison; Mizzter Blizzard wanted to control winter in order to never melt; a large Piranha Plant known as Petey Piranha simply accidentally ate his Sticker.