Kinlaw played one year at Jones County Junior College in 2016 before transferring to the University of South Carolina.[4] In his first year at South Carolina in 2017, he played in all 13 games with 10 starts and had 20 tackles.[5] In 2018, he started all 12 games and had 38 tackles and 4.5 sacks.[6] Kinlaw returned to South Carolina for his senior season in 2019.[7][8]
Kinlaw was selected by the San Francisco 49ers in the first round of the 2020 NFL draft with the 14th overall pick.[11] The 14th overall pick was acquired originally from the Tampa Bay Buccaneers after the 49ers traded down with the first round pick (13th overall) they originally acquired in the DeForest Buckner trade.[12] He signed his four-year rookie contract with the team on 26 June 2020,[13] worth a fully guaranteed $15.48 million, including an $8.8 million signing bonus.[14]
During Week 10 against the New Orleans Saints, Kinlaw recorded his first career sack on quarterback Taysom Hill during the 27–13 loss.[15] Kinlaw was placed on the reserve/COVID-19 list by the team on 18 November 2020,[16] and activated on 27 November.[17] In Week 12 against the Los Angeles Rams, Kinlaw intercepted a pass thrown by Jared Goff and returned it for a 27-yard touchdown during the 23–20 win. This was his first career interception and touchdown.[18] Kinlaw was named Pepsi Rookie of the Week for his performance against the Rams.[19] As a rookie, Kinlaw appeared in 14 games and started 12. He recorded 1.5 sacks, 33 total tackles, one interception, and four passes defended.[20] He was named to the PFWA All-Rookie Team.[21]
On 30 October 2021, Kinlaw was placed on injured reserve.[22] He played in four games on the 2021 season.[23]
On 15 October 2022, Kinlaw was placed on injured reserve.[24] He was activated on 23 December.[25] He started in all six of his regular season appearances and the 49ers' three postseason games.[26]
On 29 April 2023, the 49ers declined the fifth-year option of Kinlaw's rookie contract, making him a free agent in the 2024 offseason.[27] In the 2023 season, Kinlaw appeared in all 17 games and started six. He finished with 3.5 sacks, 25 total tackles, and three passes defended.[28]
New York Jets
On 14 March 2024, Kinlaw signed a one-year contract with the New York Jets.[29]