He played college football at Florida State, and was signed by the San Francisco 49ers as an undrafted free agent in 2018.

As a senior, he led his school to a second consecutive 5A state championship by tallying five interceptions, 41 tackles, six pass breakups, two forced fumbles and scoring five total touchdowns in four different ways (one pick six, two punt returns, one kickoff, one reception).

He was named into 5A All-State First-team and American Family Insurance Florida All-State Team honors, named the 2014 All-Broward Defensive Player of the Year and to the All-Broward County Team, and MaxPreps Medium School All-American.

As a sophomore, he took over as the starter, finishing with eight interceptions on the season, tied for the most in the country and second-most in FSU single-season history en route to first-team All-America honors from the FWAA and Phil Steele, All-ACC First-team accolades, was one of five finalists for the Bronko Nagurski Award, which is given to the nation's top defensive player, and collected the Jack Tatum Trophy, given to the nation's top defensive back by the Touchdown Club of Columbus.

[4][5][6][7] McFadden finished his junior season, totaling 30 tackles, 10 pass breakups and returning a blocked field goal 63 yards for a touchdown against Delaware State.

[20] He was released during training camp that year, but re-signed with the team in November as a practice squad member.

McFadden also started at cornerback in the 109th Grey Cup where he had four defensive tackles in the victory over the Winnipeg Blue Bombers.

In 2023, McFadden played in 15 regular season games and recorded 23 defensive tackles, two interceptions, and two forced fumbles.

[26] He started in all three post-season games, including the 111th Grey Cup where he had one defensive tackle in the Argonauts' 41–24 victory over the Winnipeg Blue Bombers.