He won a silver medal in the 110 metres hurdles with a time of 13.24 seconds at the 2013 World Youth Championships in Donetsk, Ukraine.

[4] He lost to Jaheel Hyde of Jamaica, who established a new championship record and came .01 seconds shy of tying the World Youth Best held by Wilhem Belocian.

[7] Humphrey earned the starting cornerback job in his first game against Wisconsin and ranked second on the team in interceptions with 3 during the 2015 season.

The team went on to win their 16th national championship, with Humphrey recovering a key onside kick midway through the fourth quarter of the game.

Humphrey continued to dominate opposing receivers the rest of the season, and declared his early departure from the collegiate level for the NFL draft.

He attended pre-draft visits with multiple teams, including the Philadelphia Eagles, Buffalo Bills, Dallas Cowboys, and Pittsburgh Steelers.

[23] Head coach John Harbaugh named Humphrey the third cornerback on the depth chart to begin the regular season, behind Jimmy Smith and Brandon Carr.

On October 8, 2017, Humphrey earned his first career start and recorded three combined tackles during a 30–17 win at the Oakland Raiders in Week 5.

On November 19, 2017, Humphrey recorded three combined tackles, deflected two passes, and made his first career interception in the Ravens' 23–0 victory at the Green Bay Packers in Week 11.

Humphrey made his first career interception off a pass attempt by quarterback Brett Hundley, which was originally intended for wide receiver Jordy Nelson, and returned it for a 15-yard gain in the fourth quarter.

Humphrey became a starting cornerback for the last four regular season games after Jimmy Smith was placed on injured reserve after tearing his Achilles tendon.

[28] Head coach John Harbaugh named Humphrey a starting cornerback to begin the regular season after Jimmy Smith was suspended for the first four games for violating the league's personal conduct policy.

[29] He started in the Ravens' season-opener against the Buffalo Bills and made two solo tackles and a season-high three pass deflections during a 47–3 victory.

[30] 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.

[36] In week 7 against the Seattle Seahawks, Humphrey returned a fumble lost by rookie wide receiver DK Metcalf 18 yards for his first NFL touchdown in the 30–16 win.

[37] Then two weeks later 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.

[39] 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.

He also forced a fumble on wide receiver Mike Thomas which was returned for a 53 yard touchdown by teammate Patrick Queen.