On what date was Halo 3 released for the Xbox 360?

Halo 3 was released for the Xbox 360 on September 25, 2007.

Developed by Bungie and published by Microsoft Game Studios, Halo 3 concluded the original trilogy's main conflict between humanity, the Covenant, and the Flood. It launched first in North America, followed by other regions shortly afterward. The game was marketed as the conclusion to the Reclaimer Trilogy, although later games continued the broader Halo story.

Halo 3 is sometimes confused with Halo 2 because both were major Xbox launches and both continued Master Chief's story. Halo 2 debuted in 2004 for the original Xbox, while Halo 3 was the series' first mainline entry made specifically for Xbox 360. Its release also introduced features such as Forge and expanded online multiplayer through Xbox Live.

The date is a release date, not the date of the game's announcement, beta testing, or later remastered inclusion in Halo: The Master Chief Collection.