[4] In late November 2017, it was announced that Elliott would forgo his senior year at Texas in favor of the 2018 NFL draft, and that he would not play in the Longhorns' bowl game.

[9] Throughout training camp, Elliott competed for a roster spot as a backup safety, against veterans Chuck Clark, Anthony Levine, and Kai Nacua.

Throughout training camp, Elliott competed for a roster spot as a backup safety against Anthony Levine and Brynden Trawick.

[14] He entered training camp in 2020 slated to be the primary backup safety behind Earl Thomas after Tony Jefferson was released.

[16] On September 13, 2020, Elliott earned his first career start and recorded five combined tackles (two solo) in the Ravens' 38–6 defeat over the Cleveland Browns in their home-opener.

On January 10, 2021, Elliott started in his first appearance in the postseason and made four combined tackles (three solo) as well as one pass deflection in a 20–13 victory at the Tennessee Titans in the AFC Wildcard Game.

[21] The following week, he had five combined tackles (four solo) as the Ravens were eliminated from the playoffs following a 3–17 loss at the Buffalo Bills in the AFC Divisional Round.

[22] Head coach John Harbaugh retained Elliott and Chuck Clark as the starting safety duo in 2021.

[23] On November 8, 2021, Elliott was placed on injured reserve after suffering a season-ending biceps and pectoral injury late in the fourth quarter of a 34–31 overtime win over the Minnesota Vikings in Week 8.

[24][25] He ended his last season with the Baltimore Ravens with 21 combined tackles (19 solo), two pass deflections, one sack, and one interception in six games and six starts.

[35][9] Throughout training camp, Elliott competed against close friend and former college teammate Brandon Jones for the starting role at free safety.

[36] On September 10, 2023, Elliott started the Miami Dolphins' season-opener at the Los Angeles Chargers and collected a season-high 13 combined tackles (eight solo) in a 36–34 victory.

On January 7, 2024, Elliott recorded ten combined tackles (six solo), deflected a pass, and intercepted a throw by Josh Allen intended for Gabriel Davis in a 21–14 loss to the Buffalo Bills in Week 18.