Darius Leonard attended South Carolina State University and became an immediate impact player for the Bulldogs. He led the team in tackles as a redshirt freshman before earning first-team all-conference honors as a redshirt sophomore. Leonard would add 2 MEAC Defensive Player of the Year Awards before declaring for the 2018 NFL Draft.
Leonard shined in the 2018 Senior Bowl, something he would need as he would be unable to complete all of the drills at the NFL Scouting Combine after injuring his quad during the 40-yard dash.
The Indianapolis Colts selected Leonard with their second-round pick (36th overall) in the 2018 NFL Draft. Shedding any doubts on if he was ready for the NFL, Leonard earned starter's role as the season opened up. It would only take two weeks for Leonard to earn national recognition as he compiled 19 tackles and a sack in the Colts' win against the Washington Redskins. For his impressive performance, Leonard was named AFC Defensive Player of the Week.
Leonard continued to shine in the season's opening month, earning NFL Defensive Rookie of the Month honors. Despite suffering an injury, Leonard managed to break the Indianapolis Colts franchise record for most tackles by a rookie in Week 15. He then would break the Colts franchise record for most tackles in a single season in a 33-17 win against the Tennessee Titans. Leonard once again was named AFC Defensive Player of the Week and earned AFC Defensive Player of the Month honors for December.
All told, Leonard finished an impressive rookie campaign with 163 tackles, eight pass deflections, seven sacks and an interception. He had the most tackles by a rookie in 2018 and received an overall grade of 80.3 from Pro Football Focus, which ranked him ninth among all linebackers. Leonard also led the entire NFL in combined (163) and solo (111) tackles. In just his first season in the NFL, Leonard earned All-Pro honors. On top of his accolades and recognition as one of the game's up and coming defensive stars, Leonard also earned the 2018 NFL Defensive Rookie of the Year award.