Harris attended Lloyd C. Bird High School in Chesterfield, Virginia, where he played quarterback, wide receiver and defensive back (two-time All-state and All-region selection).

Harris committed to play college football at the University of Virginia on June 2, 2010, after being recruited by then head coach Jim Reid.

Harris ended his collegiate career with 289 tackles (145 solo and 6 for loss), 11 interceptions, 2 sacks, 2 forced fumbles and 19 passes defensed.

He appeared mostly on special teams and finished the season with 14 total tackles including a season-high three stops at North Carolina.

Harris recorded 87 total tackles (48 solo and 0.5 for loss), a forced fumble, an interception and was credited with 3 passes defensed.

He also blocked a key punt in the second half of Virginia's victory against BYU and was named the Walter Camp National Defensive Player of the Week for his efforts against the Cougars.

21 Louisville to earn the first of his two ACC Defensive Back of the Week honors, with the second one coming in a win over Miami in which he recorded 10 tackles and broke up three passes.

[5][6][7] At the conclusion of the pre-draft process, Harris received a wide range of varying draft projections due to his shoulder injury.

His fall in the draft was attributed to his shoulder injury and many reporting his recovery process could possibly extend into the beginning of the regular season.

[15] Throughout his first training camp, Harris competed against Andrew Sendejo, Antone Exum, and Robert Blanton for the starting strong safety position.

On December 10, 2015, Harris made his first career start and professional regular season debut during a 23–20 loss to the Arizona Cardinals and led the team with eight combined tackles while also deflecting a deep pass attempt by Carson Palmer.

[17] The following game, he made his second consecutive start and collected five combined tackles and defended a pass in a 38–17 victory over the Chicago Bears.

[19] On January 10, 2016, Harris appeared in his first career playoff game as the Vikings lost 10–9 to the Seattle Seahawks in the NFC Wild Card Round.

[20] Harris entered training camp competing for a job as the backup safety against Michael Griffin, Exum, and Jayron Kearse.

[21] On December 11, 2016, Harris started at free safety in place of an injured Smith who suffered a severe high ankle sprain.

Due to Sendejo being suspended for a Week 8 matchup against the Cleveland Browns in London, Harris got the start again and recovered a fumble by running back Isaiah Crowell in the third quarter.

During a Week 11 matchup against the Los Angeles Rams, Harris recorded a season-high seven combined tackles after starting at strong safety with Sendejo inactive due to a groin and hamstring injury.

Harris would record two more interceptions throughout the season, which came off Philip Rivers in a 39–10 win over the Los Angeles Chargers, and Aaron Rodgers in a 23–10 loss to the Packers.

[33] In the NFC Wild Card game against the New Orleans Saints, Harris intercepted a pass thrown by Drew Brees and returned it for 30 yards during the 26–20 overtime win.

[46] After having a free agent visit the day prior, Harris signed with the Eagles on December 13, 2022, following injuries to C. J. Gardner-Johnson and Reed Blankenship.