2021 (real world)

January

 * January 27: Series 5: Anvil of Halo: The Master Chief Collection is launched.

March

 * March 2: Halo: Point of Light is released.

April

 * April 7: Series 6: Raven of Halo: The Master Chief Collection is launched.

June

 * June 13: Halo Infinite is shown at the Xbox & Bethesda Games Showcase with a new trailer.
 * June 23: Series 7: Elite of Halo: The Master Chief Collection is launched.

July

 * July 29: Halo Infinite ' s first multiplayer technical preview begins, focusing on Bot Slayer, the Academy's Weapon Drills, and UI tests. A new version of Halo Waypoint was simultaneously tested.

September

 * September 24: Halo Infinite ' s second multiplayer technical preview begins, focusing on Big Team Battle, Arena Slayer, and the Academy's training mode.

October

 * October 13: Series 8: Mythic is released for Halo: The Master Chief Collection as 2020's final season.
 * October 19: Halo: Divine Wind is released.

November

 * November 1: Halo Waypoint's "vNext" update is launched.
 * November 15
 * Halo: Combat Evolved’s and Xbox's 20th anniversary
 * The Halo Infinite Multiplayer Beta and Season 01: Heroes of Reach begin.
 * November 19: Halo Infinite is gone gold.
 * November 30: Halo: Legacy Collection, a compilation of the comic series Halo: Uprising, Halo: Helljumper and Halo: Blood Line, is published by Dark Horse Comics.

December

 * December 7: A new edition of Halo Graphic Novel by Dark Horse Comics is released.
 * December 8: Halo Infinite is released, following a delay from its original release dates of Holiday 2020 and Fall 2021.
 * December 14: The Art of Halo Infinite is released, following its delay from a 2020 release.