- March 19: Halo: Silentium, the third and final novel in the Forerunner Saga by Greg Bear, was released.
- June 10: The Halo Xbox One Announcement Trailer is shown at E3 2013.
- July 18: Halo: Spartan Assault was released for Windows 8 and Windows Phone.
- August 14: Issue 1 of Halo: Initiation was released.
- August 20: The Champions Bundle was released on the Xbox Live Marketplace.
- September: McFarlane Toys/Halo 4 Series 2 figures were released to stores.
- September 11: Issue 2 of Halo: Initiation was released.
- September 16: Halo 4: The Essential Visual Guide was released in the U.S.
- October 1: Halo 4: The Essential Visual Guide was released in Europe.
- October 9: Issue 3 of Halo: Initiation was released.
- October 29: 343 Industries announced that Halo: Spartan Assault would be coming to the Xbox 360 and Xbox One in December 2013.
- November 22: The Xbox One was released in thirteen selected markets.
- December 11: Issue 1 of Halo: Escalation was released.
- December 23 - Halo: Spartan Assault was released for Xbox One.