As a freshman, Jeffery caught five passes for 61 yards in his first five games before making seven catches for 138 yards and three touchdowns against the University of Kentucky. The performance was the second-best single-game performance in school history and Jeffery became the third Gamecock in 2009 to earn SEC Freshman of the Week, following defensive end Devin Taylor and running back Jarvis Giles. He was a consensus first-team Freshman All-SEC and first-team Freshman All-American in recognition of his successful freshman season.

In a Week 4 game against Auburn, Jeffery had a breakout performance in the 35–27 loss. He was only a few yards shy of 200 receiving yards and added two touchdowns for the Gamecocks. Another one of his best games in 2010 came against in-state rival Clemson where he had five catches for 141 yards and a touchdown. Through 14 games, Jeffery made 88 catches totaling 1,517 yards and nine touchdowns including eight games with 100 yards or more receiving, and a 108.4 yd/game average. Jeffery was named a Biletnikoff Award finalist, the award given to the nation’s top wide receiver. Because of his performances, helping lead the Gamecocks to their first SEC Championship Game appearance in school history, Jeffery was selected as an All-American.

Jeffery attended Calhoun County High School in St. Matthews, South Carolina, where he was part of a four-time state championship winning basketball team that recorded an 84–1 record. He also played two years of football and was widely recruited, giving a verbal commitment to the University of Southern California before switching his commitment to the University of South Carolina. Jeffery’s younger brother, Shamier Jeffery, committed to play football for the Gamecocks in 2011, following in the footsteps of both of Jeffery’s two older brothers Charles Ben and Darren Ben; both of whom also played basketball and football for Calhoun County High School.

At the beginning of the 2011 season, Jeffery was named by ESPN as the best overall player in the SEC. In the season opener against ECU in which he caught five passes for 92 yards, Jeffery extended his active streak to 24 consecutive games with a reception. In the 2012 Capital One Bowl, Jeffery caught four passes for 148 yards and a touchdown but was ejected in the third quarter for fighting with Nebraska player cornerback Alfonzo Dennard. Despite this, Jeffery was named the Capital One Bowl MVP.

On May 2, Jeffery and the Bears agreed to a four-year contract, making him the first player in the 2012 draft class to sign, and the earliest second-rounder to sign since Dallas Cowboys receiver Kevin Williams in 1993. Jeffery made his debut against the Denver Broncos in week one of the preseason, and caught a game-high four passes for 35 yards, though the Bears lost 31–3. In the second preseason game, Jeffery was penalized for unnecessary roughness for fighting Washington Redskins cornerback DeAngelo Hall. Jeffery was later told by coaches to “play smarter”. In his regular season debut against the Indianapolis Colts, Jeffery caught a Jay Cutler pass for a 42-yard touchdown. In Chicago’s Week 5 away game against the Jacksonville Jaguars, Jeffery left the game after catching a touchdown thrown by Cutler. Although the injury did not appear to be significant, x-rays done on the following Monday determined Jeffery broke his right hand, which led to him missing a few games. Though the injury did not require surgery, Jeffery still had to wear a cast. Jeffery eventually practiced for the first time on November 9. Jeffery returned in Week 11 against the San Francisco 49ers, but would injure his knee, and will be sidelined for 2–4 weeks. In Week 15 against the Green Bay Packers, Jeffery was penalized three times for pass interference, nullifying a touchdown and two receptions of 36 and seven yards, as the Bears lost 21–13. Jeffery ended his rookie season catching 24 passes for 367 yards and three touchdowns.

Jeffery’s season ended with 54 receptions for 807 yards and four touchdowns on 93 targets. Jeffery would end up leading the Bears in receptions in the 2015 season with 54.

On February 26, 2016, it was announced that the Bears placed the franchise tag on Jeffery. On September 11, Jeffery caught four passes for a season-high 105 yards in the season opener against the Houston Texans. Jeffery recorded a 54-yard reception. On September 19, Jeffery caught five passes for 96 yards against the Philadelphia Eagles. Jeffery recorded a 49-yard reception early in the second quarter and a 22-yard reception late in the first quarter. On October 16, Jeffery caught a season-high seven passes for 93 yards against the Jacksonville Jaguars. Jeffery recorded a 26-yard reception. On October 31, Jeffery caught four passes for 63 yards and his first touchdown of the season against the Minnesota Vikings. On November 14, the NFL suspended Jeffery for four games for violating the NFL’s performance-enhancing drug policy. On December 18, Jeffery caught six passes for 89 yards and a touchdown against the Green Bay Packers.

On March 9, 2017, Jeffery signed a one-year, $14 million contract with the Philadelphia Eagles. Jeffery made his Eagles debut on September 10, 2017 in the season opener against the Washington Redskins. He finished the game with 38 yards on three catches. In Week 2 on September 17 at Kansas City, Jeffery had 92 yards on 7 catches and one touchdown, his first as an Eagle, in a 27–20 loss to the Chiefs. On December 2, 2017, Jeffrey signed a four-year extension worth $52 million with $27 million guaranteed.

The Eagles finished the season 13–3 and earned a first round bye. In the Divisional Round against the Atlanta Falcons, Jeffery recorded 4 catches for 61 yards in a 15–10 victory. In the NFC Championship Game against the Minnesota Vikings, Jeffery caught 5 passes for 85 yards and 2 touchdowns in 38–7 victory to advance to Super Bowl LII. In the Super Bowl, Jeffery caught 3 passes for 73 yards and scored the first touchdown of the game. The Eagles went on to defeat the New England Patriots 41–33 to give Jeffery and the franchise its first Super Bowl championship. On February 21, 2018, it was revealed that Jeffery underwent surgery for a torn rotator cuff.

In Week 1 against the Washington Redskins, Jeffery caught five passes for 49 yards and the first receiving touchdown of the season as the Eagles won 32–27. In Week 2 against the Atlanta Falcons, Jeffery left early in the game due to a calf injury. He was listed as questionable to return to the game, but he did not play for the remainder of the game The Eagles lost their first game of the season 20–24. Jeffery made his return from injury in Week 4 against the Green Bay Packers. In the game, he caught three passes for 38 yards and one touchdown in the 34–27 win. Jeffery suffered a hip injury in week 9 against the Chicago Bears and was forced to miss the next two games. He made his return in Week 13 against the Miami Dolphins. In the game, Jeffery caught nine passes for 137 yards and a touchdown in the 37–31 loss. He was placed on injured reserve with a foot injury on December 12, 2019. Overall, Jeffery finished the 2019 season with 43 receptions for 490 receiving yards and four receiving touchdowns.

On July 28, 2020, the Eagles placed Jeffery on the active/physically unable to perform list to begin training camp. He was activated on September 5, 2020.