The following are known Game Genie Codes for Mortal Kombat II on Nintendo Game Boy.

• 001-57F-F72
  No continues
• 011-57F-F72
  Start with 1 continue
• 031-57F-F72
  Start with 3 continues
• 091-57F-F72
  Start with 9 continues
• 0F1-57F-F72
  Start with 15 continues
• 00D-ABF-3BE
  Infinite continues
• 02C-55B-E6E
  Much faster timer
• 00C-55B-E6E
  No timer
• 2C3-39D-800
  Timer starts at 30
• 3C3-39D-800
  Timer starts at 40
• 4C3-39D-800
  Timer starts at 50
• 5C3-39D-800
  Timer starts at 60
• 009-48B-91D
  Infinite energy
• 006-2EB-3B7 + 000-1FA-3B7
  Player cannot move from the floor
• 003-279-19E + 003-249-19E
  Computer cannot move from floor
• 3E1-79E-4CA + 031-7AE-A2A + E01-7BE-2A9
  Complete Round 1 and go to Round 3, but you have to switch off at the end of the Round to advance.
• 3E1-79E-4CA + 041-7AE-A2A + E01-7BE-2A9
  Complete Round 1 and go to Round 4, but you have to switch off at the end of the Round to advance.
• F40-E89-2AE
  Normal punches do more damage
• 311-009-3B9
  Uppercuts do less damage
• 311-3A9-E69
  Back throws do less damage
• F41-5A9-E60
  Special Moves (projectiles) do more damage