He played college football at Oregon,[1] and was selected by the 49ers in the fifth round of the 2021 NFL draft.

[5] Lenoir made his NFL debut with a start in the 49ers' season opener against the Detroit Lions.

[8] In the 2022 season, Lenoir finished with one sack, 79 total tackles, one interception, and five passes defended in 17 games and 13 starts.

[13] In Super Bowl LVIII, he recorded eight total tackles and a forced fumble in the 25–22 overtime loss to the Chiefs.

[14] In Week 5 of the 2024 season, Lenoir recorded his first career touchdown on a 61-yard blocked field goal return in a 24–23 loss to the Arizona Cardinals.