The Chao Garden is a place where the A-Life creatures, the Chao, reside. Chao Eggs are deposited in an inaccessible garden that can only be viewed through a menu screen. Once the Chao has hatched, the player can equip it with a fighting character in order to give the bonded character special abilities.
The Chao Garden is included in Sonic Adventure, Sonic Adventure DX, Sonic Adventure 2 and Sonic Adventure 2: Battle. The garden can be linked to Sonic Advance and Sonic Advance 2, and is also included in Sonic Pinball Party in the form of the Tiny Chao Garden. Sonic Chronicles: The Dark Brotherhood also features a Chao Garden, although it is inaccessible, unlike in the Adventure games. In Sonic Chronicles, the player can collect Chao Eggs scattered throughout the game's maps.
In Sonic Adventure, there are three gardens available: one in the hotel in Station Square, one inside the cave in Mystic Ruins, and one on the beach near the Egg Carrier. In Sonic Adventure 2, there is also a Hero Garden and a Dark Garden, in addition to a Neutral Garden. These are unlocked when the player has at least one Hero Chao and at least one Dark Chao in their possession. The Chao Garden in Sonic Adventure 2 contains a rock formation and a waterfall that leads to the Chao cave. The player can bring Chao back and forth between the gardens in Sonic Adventure DX and Sonic Adventure 2 via the Tiny Chao Garden on the Game Boy Advance.
- The Chao Gardens use an updated version of the A-Life system originally used in NiGHTS into Dreams' nightopian system.
- Highway signs in Crisis City in Sonic the Hedgehog point to a Chao Garden, although the actual garden is never seen.