The following are known Action Replay Codes for Metroid: Zero Mission 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
d925cbb3
457d65d3
b6fa891b
dc4362a9

Have All Extras Unlocked
3e36528f
9c8585f2

Have All Weapons & Bombs
2a78e597
6edeacb7

Have All Suits & Misc Items
07268fae
26d2f696

Invincibility
7b1f1183
0a99a175

Max Health
a2fe6a98
e1bf858a

Infinite Health
40138275
1cef5c04

Max Missiles
ef5591c4
96ef829f

Infinite Missiles
56b8177f
5e5fb2a2

Max Super Missiles
021957c8
81db0ac3

Infinite Super Missiles
22cf39bf
6d1d9940

Max Power Bombs
fceade53
78e11c69

Infinite Power Bombs
700e2024
1b725001

No Suit
ac1c686b
69b7a733