The Big Mushroom is a unique item in Super Mario Maker. It can be placed in the editor only by setting the 8-Bit Mario 30th Anniversary Amiibo (included with the Super Mario Maker Amiibo pack) on the reader. A single Big Mushroom is then placed in the editor. If you use the one with the classic color scheme, you get one that looks like a super mushroom from the original Super Mario Bros.. If you use the one with the modern color scheme, it will look like a modern super mushroom. Costume Mushrooms unlocked by Amiibos, the Big Mushroom does not unlock when placed; the Amiibo must be used every time you wish to place one.
When the Big Mushroom is collected, Mario becomes Big Super Mario, which has the following effects:
- Mario doubles in size in both dimensions, quadrupling in size.
- If the mushroom is the modern style, Mario will have a modern color scheme.
- Mario can break blocks by jumping into them from below, as regular Super Mario. He can also break blocks by running into them.
- Enemies look different. If Mario is hit, he reverts to normal Mario, as Super Mario normally would.
- An artificial CRT TV border and raster filter is applied to the display.
When placed, the game style changes to Super Mario Bros., but you can then switch it to a different game style and it will stay, but not do anything.