Nintendo has released many add-ons for the Game Boy Advance (GBA). These include:

Wireless Adapter - Released in 2004, this adapter hooks up to the back of the Game Boy Advance. It replaces link cables and allows many people to link up to each other. It markets for $20 and came included with Pokémon FireRed and Pokémon LeafGreen. Because it was released so late in the GBA's life, less than 20 games support this hardware. The adapter's usefulness is most evident in Pokémon; FireRed/LeafGreen and Emerald feature a "Union Room" where up to forty people can enter to battle or trade Pokémon. The adapter itself was not backward compatible, leading to criticism that this accessory was more novel than useful, only available on a few games. A Game Boy micro version has also been released - it can interact fully with both models of the Wireless Adapter.

Game Boy Advance Infra-Red Adapter - This adapter was included with the game Ciberdrive Zoids as it is only compatible with this game. The adaptor was not sold separately.

Play-Yan - The Play-Yan is an MP3/MPEG4 player for the GBA and Nintendo DS. The cartridge is slightly bigger than normal GBA cartridge and includes a built-in headphone port as well as an SD Card slot. Music or videos that users have downloaded from the Internet can be transferred onto an SD Card and slotted into the Play-Yan device. Nintendo has released several mini games for the Play-Yan that can be downloaded from their website, although Nintendo later removed all mini-game functionality through a firmware update. The Play-Yan is currently available in Japan only, but a European release has been confirmed for early 2006. Since Play-Yan did not have a U.S. release to coincide with Game Boy micro as rumored, an American release has been speculated for 2006 as well.

e-Reader - The e-Reader is a rather bulky scanning device that plugs into the game cartridge slot of the Game Boy Advance. Specialized cards with codes along the side and bottom are slid through the slit, scanning the card into the Game Boy Advance. Many ideas for the e-Reader have included cards that scan classic games like Donkey Kong and Excitebike onto the handheld ready to play, as well as a collaboration with Super Mario Advance 4 to have cards that unlock content. GameCube games like Animal Crossing had cards with unlockable content as well, and the Pokémon Trading Card Game playing cards also adopted the e-Reader codes. The e-Reader works with the Game Boy Player as well as the Game Boy Advance SP, but cannot fit into the Nintendo DS's Game Boy slot. It was discontinued in America in early 2004, but is still quite popular in Japan. It was not released in Europe.

Game Boy Advance Video - These highly popular cartridges contain two episodes of 30 minute cartoon programs. First released in America in May of 2004, they cost $19.99 and included cartoons such as Pokémon, SpongeBob SquarePants, Sonic X, and Teenage Mutant Ninja Turtles. The movies Shrek, Shrek 2, and Shark Tale are also available for GBA Video and all three movies are in full. Unfortunately, these cartridges display an error when inserted into a GameCube via a Game Boy Player.
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Unofficial accessories

GBA Movie Player - The GBAMP is a versatile gaming cartridge that allows people to play NES/Famicom games, watch movies (e.g. MPEGs), see .txt files, hear sound clips, etc. The GBAMP does not actually play MPEGS or MP3's directly, a freeware conversion software is needed, that converts an array of formats into GBM and GBS formats that are compatible with the GBAMP.

TV Tuner - It makes the portable system into a portable television. There are several versions (made by different companies) available. The most popular TV Tuner requires a cartridge in the GBA unit to start up. The TV Tuners can store up to 99 channels.

Unofficial Game Boy Advance flash cartridges are also available. While they enable the distribution of homebrew applications and content, they may also facilitate the illegal distribution of copyrighted games.