[5] On January 24, 2015, Diggs played in the 2015 Senior Bowl and recorded four solo tackles and an interception as part of Ken Whisenhunt's North team that defeated the South 34–13.

[7] On March 24, 2015, Diggs attended Texas's pro day, but opted to stand on the majority of his combine numbers and only performed positional drills and broad jump.

At the conclusion of the pre-draft process, Diggs was projected to be a seventh round pick by the majority of NFL draft experts and scouts.

[15] Throughout training camp, Diggs competed for the role as the first-team nickelback against Bill Bentley, Nevin Lawson, and Mohammed Seisay.

[16] Head coach Jim Caldwell named Diggs the backup nickelback, behind Nevin Lawson, to begin the regular season.

[17] He made his professional regular season debut in the Lions' season-opener at the San Diego Chargers and recorded two solo tackles in their 33–28 loss.

[20] On November 22, 2015, Diggs collected a season-high six combined tackles and a pass deflection in the Lions' 18–13 win against the Oakland Raiders in Week 11.

[24] Defensive coordinator Teryl Austin named Diggs the first-team nickelback and third cornerback on the depth chart to start the season, behind Darius Slay and Nevin Lawson.

[26] On December 6, 2016, the Detroit Lions placed Diggs on injured reserve after he suffered a pectoral injury during a Week 13 victory at the New Orleans Saints.

[29] Head coach Jim Caldwell named Diggs the first-team nickelback on and the fifth cornerback on the Lions' depth chart, behind Darius Slay, Nevin Lawson, Teez Tabor, and D.J.

[31] On December 3, 2017, Diggs started his first game as a strong safety and collected five solo tackles and a pass deflection during a 44–20 loss at the Baltimore Ravens in a Week 13.

[35] On September 10, in the season opener on Monday Night Football, Diggs intercepted Sam Darnold's first career pass attempt and returned it 37 yards for a touchdown in a game against the Jets.

[41] In Week 1 against the Atlanta Falcons, Diggs intercepted a pass thrown by quarterback Matt Ryan late in the fourth quarter to seal a 38–25 Seahawks' win.

[43] In Week 7 against the Cardinals on Sunday Night Football, Diggs recorded an interception off a pass thrown by Kyler Murray during the 37–34 overtime loss.

[44] In Week 12 against the Eagles on Monday Night Football, Diggs intercepted a pass thrown by Carson Wentz in the end zone during the 23–17 win.

[45] Diggs was named to the Pro Bowl on December 21, 2020, as the National Football Conference (NFC) starter at free safety.