During his freshman year, former NFL player Frank Middleton, who was an assistant coach, convinced him to join the football team.

Arnold ended up becoming an All-State selection at cornerback, in addition to earning District Offensive MVP honors as a quarterback and wide receiver.

As a junior in 2018, Arnold also suffered an ankle injury which ended the season after four games, forcing him to redshirt.

[8] in the 2020 NFL draft, Arnold signed a three-year deal with the Philadelphia Eagles on April 26, 2020.

[6] He was named the Eagles' best undrafted free agent by CBS Sports, with scouts praising his versatility.

[13] Arnold was elevated to the active roster on September 26 for the team's week 3 game against the Cincinnati Bengals.

[22] On December 11, Arnold was elevated to the active roster from the practice squad and made his debut against the Seattle Seahawks.

[25] On January 3, 2022, Arnold was placed on injured reserve after suffering an ankle injury in the team's week 16 game against the 49ers.