He played college football for the Oklahoma State Cowboys, twice earning unanimous All-American honors before being selected by the Jaguars fifth overall in the 2012 NFL draft.

He attended Plainview High School in Ardmore, Oklahoma,[1] where he was a four-sport star in football, basketball, baseball and track.

Statistically, Blackmon caught 111 passes for 1,782 yards and 20 touchdowns in 12 games during the 2010 season and also added a pair of scores with a 69-yard run and a blocked punt return.

[8] Despite the extreme defensive game plans geared specifically at stopping him, he emerged as the Biletnikoff Award winner as the nation's top receiver for the second consecutive season; former Texas Tech receiver Michael Crabtree is the only other player to win the Biletnikoff Award twice.

[13] Source:[14] Blackmon decided not to participate in any workouts at the NFL Combine, instead performing at Oklahoma State's Pro Day.

[25] On June 3, 2012, Blackmon was arrested for driving under the influence (DUI) of alcohol in Stillwater, Oklahoma and was released from custody later that day.

[26] On April 20, 2013, Blackmon received a four-game suspension by the NFL for violating the league's substance abuse policy.

The Jaguars placed him on the physically unable to perform (PUP) list in which he missed training camp and the start of the preseason.

Blackmon returned to the active roster and practiced on August 12, however he missed the first four games of the regular season due to his suspension.

[28] On November 1, during the Jaguars' bye week, he was suspended indefinitely without pay for again violating the NFL's Policy and Program for Substances of Abuse.

On May 2, 2014, Jaguars general manager David Caldwell announced that it was unlikely that Blackmon would join the team for the 2014 season.

[30] On October 1, 2014, Jaguars head coach Gus Bradley said Blackmon had voluntarily checked into a 90-day program, adding that he had completed nearly half of his commitment, was doing very well and learning a lot.

[33][34] That same month Blackmon was added to the Toronto Argonauts' "confidential" negotiating list before the NFL disallowed it due to his suspension.