A black screen, which appears after users load the latest update of the online multiplayer game, reads: "Our community is hurting. The systemic inequalities our community experiences are once again center stage."
The statement from developer Infinity Ward continues: "Call of Duty and Infinity Ward stand for equality and inclusion. We stand against the racism and injustice our Black community endures. Until change happens and Black Lives Matter, we will never truly be the community we strive to be."
The addition comes after Infinity Ward said it was detecting and removing a significant amount of racist content.
The company outlined a number of new steps it would take to root out the problem, including permanently banning repeat offenders.
"Call of Duty" also postponed two scheduled launches of new products earlier in the week, referencing the ongoing protests for racial equality and saying that "now is not the time" to debut the products.
"Call of Duty: Modern Warfare," which came out last September, has sold more copies than any other "Call of Duty" title at this point after its release, Activision Blizzard said last month. Fans of the game love it for its realistic military gameplay.
"Warzone," a free-to-play installment of the "Modern Warfare" game, was released in March.