Mario Circuit is a stage in Super Smash Bros. Brawl, with the stage taking place on the 8-figure intersection of the course resembling the Figure-8 Circuit from Mario Kart DS. The stage is set up with two levels; the bottom level, which is a flat surface across the race course, and the upper level, which takes place on a few platforms of the race course. On occasion, go-karts driven by Shy Guys (the ones from DS Download Play of Mario Kart DS) will race along the back or sides of the stage, crashing into characters, damaging them greatly. When they come in from the back, they will hit the bottom level, and when coming from the left, they will hit the upper level. Players can keep track of where the Shy Guys are from the screen in the back of the stage. However, like in Mute City and Onett from Super Smash Bros. Melee, the Shy Guys can be knocked aside with items, such as the Home-Run Bat. In the background of the stage, there is a big screen which shows the racers' positions on the track (by which fighters can guide themselves as to where to stay, if on the upper or the lower section).
 Songs in My Music
A song of Mario Circuit from Brawl.
 Songs Not in My Music
- In the trailer that originally revealed Mario Circuit, the Shy Guys were all driving white karts and the screen in the background was blank. Since then, the radar has been added to the screen and the eight Shy Guys participating are now paired, with the kart colors being either green, blue, orange or white.
- Players can affect the way the race turns out. If the player attacks or fling themselves in front of anyone except the Shy Guy in the lead, the leading Shy Guy could get so far ahead, that as it flies over the stage, the others are coming below it.
- In Mario Kart DS, on the Touch Screen map, the logo of a particular cup will float about underneath the map and names (for example, multiple mushrooms will float around for the Mushroom Cup, stars for Star Cup, and so on). In Super Smash Bros. Brawl, the symbol of the Super Smash Bros. series is displayed instead.