The Chiefs also elevated DE Demone Harris to their active roster.
Gay, 23, is a former second-round pick in the 2020 NFL Drat. He agreed to a four-year, $5,271,046 contract with Kansas City and is set to earn a base salary of $849,593 this season and $1.08 million in 2022.
He suffered a torn meniscus in the AFC Championship game and finished the playoffs on the injured reserve.
In 2020, Gay appeared in all 16 games for the Chiefs and recorded 39 tackles, a sack, a forced fumble and three passes defended.