He played college football at UCF and was signed by the Buffalo Bills as an undrafted free agent in 2011.

Aiken scored for the first time in his career in a Week 6 game on October 12, 2014, against the Tampa Bay Buccaneers, catching a 17-yard touchdown pass.

In Week 17, Aiken caught a 2-yard touchdown pass to seal a win over the division rival Cleveland Browns, and the Ravens clinched the AFC's final playoff spot.

In the Divisional Round of the playoffs, the Ravens took on the number-one seeded New England Patriots, one of Aiken's former teams.

In his second year after the departure of Torrey Smith, Aiken was expected to compete for a starting spot.

As a result of injuries to Steve Smith Sr., Breshad Perriman, Dennis Pitta, and Crockett Gilmore, he would end up being the Ravens' leading receiver during the year.

Aiken scored his first touchdown of the season in a Week 4 Thursday Night Football matchup with the division rival Pittsburgh Steelers.

In Week 6, in a 25–20 loss to the San Francisco 49ers, Aiken had three catches for 22 yards and a 2-yard touchdown, which he caught while diving backwards in the endzone.

Baltimore's Brent Urban would block a Travis Coons kick that would be recovered by Ravens' safety Will Hill and returned 64 yards for the game-winning touchdown.

On the final play of the first half, the Ravens ran a Hail Mary play, due to their 17-point trailing deficit, in which quarterback Jimmy Clausen lofted a pass to Aiken, who caught the ball for a 48-yard touchdown and made the game 24–14 in favor of Kansas City heading into halftime.