McKinley originally committed to the University of California, Berkeley but was ruled a non-qualifier and attended Contra Costa College. During his one season at Contra Costa College in 2013, he had 33 tackles and 10 sacks. In September 2014, he transferred to the University of California, Los Angeles. He played in 10 games that season, making one start, and finished the year with 2.5 sacks. As a junior in 2015, McKinley started 12 of 13 games, recording 35 tackles and 3.5 sacks. As a senior in 2016, he recorded 10 sacks.
Professional career
McKinley was invited to the NFL Combine as an outside linebacker and completed all the combine drills except for the short shuttle and three-cone drill. He went under surgery to repair a torn labrum and a fracture in his shoulder socket after the combine. His recovery time was expected to take four to six months, making him unable to participate at UCLA's Pro Day. NFL draft experts and analystas projected McKinley to be selected in the first or second round. He was ranked the second best outside linebacker in the draft by NFL analyst Bucky Brooks, the third best outside linebacker by NFLDraftScout.com, the fourth best edge rusher by NFL analyst Mike Mayock, the fifth best edge rusher by Sports Illustrated, and was ranked the fifth best defensive end by ESPN. McKinley was drafted by the Atlanta Falcons in the first round of the 2017 NFL Draft. On May 11, the Falcons signed McKinley to a four-year, $10.21 million contract with $7.89 million guaranteed and a signing bonus of $5.57 million. He played in all 16 games, recording 20 tackles and six sacks, good for fourth in the league among rookies and second on the team behind Adrian Clayborn. In Week 4 of the 2018 season, against the Cincinnati Bengals, McKinley recorded a career-high three sacks in the 37–36 loss. He finished the season with 22 combined tackles and a team-high seven sacks. In 2019, McKinley played in 14 games with 13 starts, recording 29 tackles and 3.5 sacks. He suffered a shoulder injury in Week 15 and was placed on injured reserve on December 17, 2019. On April 29, 2020, the Falcons declined the fifth-year option on McKinley's contract.
