He played college football for the Mississippi State Bulldogs and was selected by the Houston Texans in the second round of the 2015 NFL draft.

Eventually accepting the Bulldogs' scholarship offer,[2] McKinney became the first Rosa Fort player to sign with an Southeastern Conference (SEC) program since 2001.

Before the start of the pre-draft events, McKinney was ranked as the second best linebacker in the draft by NFL analyst Mike Mayock.

[10] On March 4, 2015, he attended Mississippi State's pro day, but opted to stand on his combine numbers and only performed positional drills for the team representatives and scouts from 29 NFL teams, including New York Jets defensive coordinator Kacy Rodgers and New Orleans Saints assistant head coach Joe Vitt.

[11] As a highly sought after prospect, McKinney attended private visits and workouts with multiple NFL teams, including the Philadelphia Eagles, Dallas Cowboys, San Francisco 49ers, Baltimore Ravens, Miami Dolphins, Carolina Panthers, Cleveland Browns, Denver Broncos, Saints, Chicago Bears, and Minnesota Vikings.

[23] He entered training camp competing against veterans Akeem Dent, Mike Mohamed, and Jeff Tarpinian for a job as a starting inside linebacker.

[24] Head coach Bill O'Brien named McKinney the backup inside linebacker behind Brian Cushing and Akeem Dent to start the regular season.

[25] He made his professional regular season debut in the Texans' season-opener against the Kansas City Chiefs and recorded one solo tackle in their 27–20 loss.

The following week, he recorded seven combined tackles and made his first career sack on Andrew Luck in the Texans' 16–10 win at the Indianapolis Colts.

[30] On September 22, 2016, McKinney recorded a career-high 16 combined tackles (ten solo) and a sack on Jacoby Brissett as the Texans were routed by the Patriots 27–0.

[31] McKinney was awarded second-team All-Pro after finishing the regular season as the only inside linebacker in the NFL with at least 100 tackles and five sacks.

On January 7, 2017, the Texans played the Oakland Raiders in the AFC wild card game and McKinney recorded seven tackles in a 27–14 victory.

They were eliminated from the playoffs the following week after being defeated by the eventual Super Bowl LI Champions, the Patriots]] in the AFC Divisional Round.

The following week, McKinney collected six combined tackles and sacked quarterback Andy Dalton twice in the Texans' 13–9 win at the Cincinnati Bengals.