He started in the Baltimore Ravens' season-opener against the Buffalo Bills and made two solo tackles and a season-high three pass deflections during a 47–3 victory. He finished the season playing in 14 games with eight starts, recording 37 combined tackles, a forced fumble, and a team-leading 15 pass deflections and two interceptions. He was given a grade of 80.0 by "Pro Football Focus", which ranked 11th among all cornerbacks. In 2019, Humphrey changed his jersey number from 29 to 44 to accommodate the signing of Earl Thomas for the 2019 season. In week 1 against the Miami Dolphins, Humphrey intercepted Josh Rosen once as the Ravens won 59–10. In week 4 against the Cleveland Browns, after getting into an altercation with Odell Beckham Jr., Humphrey pinned him to the turf. Initially, it appeared that Humphrey choked Beckham Jr., but the Ravens released a close-up video after the game that showed Humphrey had two fists full of jersey and did not touch Beckham Jr.'s neck. After the game, Humphrey apologized to Beckham and said that his response to Beckham was not a brand of football he wanted to represent. In week 5 against the Pittsburgh Steelers, Humphrey forced wide receiver Juju Smith-Schuster to fumble the ball and recovered the ball. Humphrey's forced fumble set up a game-winning field goal by Justin Tucker in the 26–23 win. In week 6 against the Cincinnati Bengals, Humphrey recorded an interception off Andy Dalton in the 23–17 win. In week 7 against the Seattle Seahawks, Humphrey recovered a fumble for an 18-yard touchdown on a ball lost by rookie wide receiver DK Metcalf in the 30–16 win. In week 9 against the New England Patriots, Humphrey recovered a fumble forced by teammate Patrick Onwuasor on wide receiver Julian Edelman for a 70-yard touchdown in the 37–20 win. This was Humphrey's second touchdown in two games. The 70-yard fumble recovery touchdown set the record for longest in Baltimore Ravens team history. In week 16 against the Cleveland Browns, Humphrey intercepted a pass thrown by Baker Mayfield late in the fourth quarter which sealed a 31–15 Ravens' win. At the end of the regular season, Humphrey had been named to the Pro Bowl and the AP 2019 All-Pro Team  On April 28, 2020, the Ravens exercised the fifth year option on Humphrey's rookie contract. After his rookie season in 2017, Humphrey decided to move back in with his parents in Alabama to finish his degree at the University of Alabama.