- Not to be confused with Mushroom World.
World Mushroom is the second Special World and the tenth world overall in Super Mario 3D World. It sits adjacent to World Flower, made up of remixes of previous courses. It is unlocked after clearing Cosmic Cannon Cluster in World Star. This world contains seven regular courses and one Mystery House.
- World Mushroom-1: Night Falls on Really Rolling Hills
- World Mushroom-2: Spiky Mount Beanpole
- World Mushroom-3: Deep-Black Jungle Drift
- World Mushroom-4: Trouble in Shadow-Play Alley
- World Mushroom-5: Back to Hands-On Hall
- World Mushroom-6: Gigantic Seasick Wreck
- World Mushroom-7: Broken Blue Belly Belt
- World Mushroom-Mystery House: Mystery House Brawl