Ross attended Jordan High School in Long Beach, California. He played wide receiver
and cornerback in football and also ran track. As a senior, Ross finished third in the 100 meters at the 2013 CIF Southern Section Division 1 final.
Regarded as a four-star recruit by ESPN, Ross was ranked as the No. 49 overall prospect in the state of California. He committed to the University of Washington to play college football.

Ross played in all 13 games as a true freshman at Washington in 2013. He finished the year with 16 receptions for 208 yards and one touchdown as a receiver and had 720 kick return yards and a touchdown. In 2014 he played in 13 of 14 games, with seven starts as a receiver and four as a cornerback. That season he had 17 receptions for 371 yards and four touchdowns as a receiver, 12 tackles and an interception as a cornerback and had 938 return yards and two touchdowns. Ross missed the 2015 season after suffering a torn ACL during spring practices. Ross returned from the injury in 2016 and had five receptions for 90 yards with two receiving touchdowns and a kick return touchdowns in his first game back. On January 3, 2017, Ross announced his decision to forego his senior season and enter the NFL Draft.

At the 2017 NFL Combine, Ross ran a 4.22 second 40-yard dash, breaking the record of 4.24 seconds held by Rondel Menendez and Chris Johnson.