Dark Chao are similar in size to Neutral Chao or Hero Chao, but have their own distinguishing features. First of all, they have a dark red-brown color with magenta and violet edges on their hands and feet. Also, instead of a small mark at the center of their belly, there is a light pink mark in the shape of a crescent the top of its chest, similar to Knuckles.
Dark Chao have a pink spikeball hovering above them instead of a sphere. They also have wings just like any other Chao, but they resemble bat wings. The eye colors are similar to a Hero Chao's, but the black outline has been replaced with sky blue. The pupils are still colored white, however.
To get a Dark Chao, one must feed it Dark Fruit and raise that Chao with Shadow, Rouge, and Dr. Eggman. Dark Fruit can be bought at the Black Market at the Chao Kindergarten in Sonic Adventure 2: Battle. In Sonic Adventure DX, and they can be found in the Black Market as well, and they are now required to get a Dark Chao because only heroic characters can be played in that game. A Dark Chao can also evolve into a Dark Chaos Chao, also known as a Devil Chao, but it can only evolve this way during the its third evolution. After it has been reborn twice, one must give the Dark Chao one of every small animal (contrary to popular belief, you can give it just a few Chaos Drives). It will then evolve into a Dark Chaos Chao.
A Dark Chao also appears in Sonic Heroes, throwing mines at the player during the Special Stages. They also appear in Mario & Sonic at the Olympic Winter Games, giving the player several missions.
In Sonic Rivals, the card with the Devil Chao mistakenly says Dark Chao.