- "The biggest free content drop in Call of Duty history."
- — Official description
Season One is the first batch of post-launch content for Call of Duty: Modern Warfare released in December 3, 2019 on all platforms. The content is focused on the story taking place after the successful Armistice's Operations in Verdansk ,with the escalating tension between Allegiance and Coalition forces and the discovery of a potential deadly weapon linked with Al-Asad whereabouts.
The first patch at launch brought some maps across the Multiplayer and Spec Ops game modes, the new Battle Pass system alongside the store and cosmetic items, while a "Refresh" update was released in December 18, 2019 with the remaining content scheduled for this season.
Originally set to end on February 4th, 2020, Infinity Ward announced, on January 15th, the season would be extended by a week and would end on February 11th, 2020. 
- Main article: Battle_Pass#Call of Duty: Modern Warfare
- Reinforce - A hybrid of Dom and S&D, a single-life mode with both teams competing for control of three flags.
- Gunfight O.S.P. - A tactically rich 2v2 mode with a twist: Begin with just your fists, and gather equipment as the match progresses.
- Infected - It’s hunt or be hunted in this survival party game mode!
- Drop Zone - Hold the Drop Zone to earn points and Drone Packages
- Cranked - Kills give you speed perks and activate a bomb countdown on your character. Chain kills to refresh your countdown and earn 2x scoring for your team.
- Grind - Recover dog tags and take them to the objective marker to score for your team.
- Gunfight 1v1
- Deathmatch Domination
- 2v2 Grind Faceoff