The main game mode in LEGO Racers is the Circuit Mode. Each Circuit has four tracks and the player objective is to win each track and be the player with the most points at the end of the circuit. There are five AI-controlled drivers in each circuit and points are given the following way: 30 points for the winner, 20 for the second-placed, 10 for the third, three for the fourth, two for the fifth and one for the sixth and last. If a racer does not finish, as the race "ends" when the player-controlled racer finishes, they will be given a certain finishing place depending on their rank: the "circuit champion" gets second place, followed by the racer who "matches up" to the first course (example: as Governor Broadside "matches up" to Imperial Grand Prix, the first course in Circuit 1, he will be given third place). In Circuit 4, 5 and 6, since the races are in an inverted order, the exact opposite applies.
Each circuit has a special driver, a "circuit champion", who is the best player in that particular circuit. The seventh circuit is different from the others, as it comprises only one track. All leaders have a color LEGO Brick that they prefer (see Power-Up Bricks). At the start of the game, only the first circuit is available. Each of the following circuits will be unlocked as the player finishes first or second in the previous circuit. By finishing a circuit in first place the leader's car set and appearance are unlocked in the Building menu. Every track also has a shortcut hidden somewhere in it, that none of the AI characters can use, excepting Veronica Voltage, the Time Race champion. "Knightmare-athon" is the only track to have no shortcut.