The following are known Action Replay Codes for The Legend of Zelda: The Minish Cap 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
77079181
cf77d17e
56c938d1
7ffb0875

Infinite Health
5cb4a820
19d7b24d

Max Health
253d28c7
015f1cfb

Max Rupees
dd955f93
ad8dc2c1

Have All Sword Techniques
37d3d776
741f4b90

Infinite Small Keys
095b38c8
85b24ad0

All Accessories
1a34f7c2
25678d8c

Infinite Bombs
180e2ff5
09f89c98

Infinite Arrows
96d82ea0
2cf7e428

Complete Hyrule Map
990c5142
c2628023

Have Dungeon M/C/BK
e5cfb7d8
6f84cb23

DON’T USE UNTIL YOU
2c35cec1
3efe80b3

HAVE THE MINISH CAP
2c35cec1
3efe80b3

Have All of the Best Items
38791c5a
da065dda
526a6c4b
1f3dcc1c

Press L + Down: Mini Mode
ac7b5895
18ae407e
65a36492
126d805a
7e6eff08
3f4dba64
937f9248
921138be
f424eb13
b0f08c18
1239c78f
25d36fe5
67c52feb
72b22a4e
66cd949b
a09efc0d
31da4297
66111a37
1e27d83b
bbfb6923

Press L + Up: Normal Mode
d52a24cf
089075be
7ad8c06d
cf5b667e
7e6eff08
3f4dba64
7262650a
5d5c91ca
45baf67e
d69b5737
d9aa1f37
ab5e3c89
bc6ade67
aa09cf4d
66cd949b
a09efc0d
33dcf44e
4e5c5464
1e27d83b
bbfb6923