Kirksey signed to the Bills' practice squad after cuts to 53-man rosters included the Houston Texans cutting the linebacker. He spent the first two weeks of the season on the practice squad and did not play in a game or get elevated in Buffalo.
Drafted by the Cleveland Browns in the third round in 2014 out Iowa, Kirksey, 31, spent the first six years of his career with the Browns. He started 54 games and had two seasons with 135-plus tackles in Cleveland. He then spent one season with the Green Bay Packers (2020), starting 11 games, and the following two years with the Texans, starting 29 games. In Houston, Kirksey was a team captain in 2022 and the team's nominee for the Walter Payton Man of the Year award. He dealt with a strained hamstring in Texans training camp this year.
Kirksey finished his career with 778 total tackles, 16.5 sacks, 45 tackles for loss and 33 passes defensed.
The Bills signed linebacker A.J. Klein back to the practice squad in a corresponding move. Klein spent all the offseason and camp with the team before being cut at the deadline. He signed back with the Bills late last season and was with the team in 2020 and 2021.
Kirksey is the second Bills player to announce retirement plans since training camp. Offensive lineman Brandon Shell retired in August.