The following are known Code Breaker Codes for Need for Speed Underground on Nintendo Game Boy Advance (GBA).

These codes are for the U.S. version of the game.

• Master Code – Must Be On
  00000000 0002
  1006C284 0007
• Infinite Credits
  820008D4 FFFF
  820008D6 7FFF
• Unlock All Upgrades/Cars/Tracks
  82000838 FFFF
  8200083A FFFF
• Race Time Is 0:0:01 (You Win The Race)
  83005F0C 0000
  83005F0E 0000
• Drift Score is 999,999
  83006A24 423F
  83006A26 000F
• Drift Multiplier is 99
  33006A0C 0009