The following are known Action Replay Codes for Blackthorne on Nintendo Game Boy Advance (GBA).
These codes were also known as GameShark Codes and in most cases will work on both devices.

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

Master Code – Must Be On
915ced5d
2d863cb1
d06e6397
4a27be2a

Infinite Health
1f53ee88
7c32846b

Have Hover Bomb
d5b864e4
1aee552a

Have Fire Bomb
f20e4b58
cf01199f

Have Remote Wasp
50494ba7
c58ef89b

Have Heal Potion
339cdf89
ca085fa2

Have Levitator
9ba49ee8
9299b3ce

Have Bridge Key
9766321e
24b9b4a0

Have Iron Key
b07023b7
38cb7d84