After graduating in 1983, and playing four years at Tennessee State University, Dent was drafted in the eighth round by the Bears, with 203rd overall pick in the 1983 NFL Draft. At 6 ft 5 in, 265 lb (120 kg), Dent was a great pass rusher who beat offensive tackles with his speed. He was part of the core of great players who made the Bears' defenses of the 1980s legendary. Between 1984 and 1985, Dent recorded 34.5 sacks, while recording a team-record 17.5 sacks in the former season.
In the 1985 season, Dent and the Bears had one of the most spectacular seasons in NFL history, finishing the season with a 15-1 record and shutting out both their opponents in the playoffs. Dent was a major factor in Chicago's success, leading the NFL with 17 sacks, while recovering two fumbles and intercepting two passes (one of which was returned for a touchdown).
In the 1985 playoffs, Dent was phenomenal, performing in what was quite possibly the most impressive defensive postseason performance in history. In the divisional playoff game in which the Bears hosted the New York Giants, Dent recorded seven tackles, three and a half sacks, and two forced fumbles. In the NFC Championship Game, Dent, along with teammate Wilber Marshall, provided one of the most memorable playoff moments in history. Late in the 4th quarter and snow just starting, quarterback Dieter Brock dropped back to pass, but Dent got there and sacked him, knocking the ball loose. Marshall picked up the loose ball and returned it for a touchdown, a moment said to be a perfect end to the Bears' season (at home) and others say the snow was "Papa Bear" George Halas giving his thumbs-up to the team. When the Bears went on to defeat the New England Patriots in 46-10 landslide in Super Bowl XX, Dent was selected as the game's MVP. During the game, he shared 1.5 sacks, forced two fumbles, and blocked a pass. Dent made a mere $90,000 in base salary for his efforts in 1985. ($173,000 in 2007 dollars and just over $192,000 in 2012 dollars ). He was a featured soloist of the "Shuffling Crew" in the video, the "Super Bowl Shuffle" in 1985:
"The sackman's comin', I'm your man Dent.
If the quarterback's slow,
He's gonna get bent.
We stop the run, we stop the pass,
I like to dump guys on their ass!
We love to play for the world's best fans,
You better start makin' your Super Bowl plans!"
Dent won another Super Bowl ring after spending the 1994 season under contract with the 49ers, though he spent almost the whole year injured. Injuries would continue to hamper Dent after his return to Chicago in 1995. He would spend 1996 and 1997 with the Indianapolis Colts and Philadelphia Eagles, respectively, playing the so-called designated pass rusher for them.
Dent retired after the 1997 season. His lifetime statistics included 137.5 sacks and eight interceptions; he returned these picks for 89 yards and one touchdown. He also recovered 13 fumbles, returning them for 56 yards and one touchdown. He had 124.5 sacks during his first stint with the Bears, from 1983 to 1993. At the time of his retirement, his 137.5 sacks ranked him third in NFL history behind Reggie White and Bruce Smith.
Dent has been nominated numerous times for the Pro Football Hall of Fame. In 2005-2009, he was among the top 15 finalists in the selection process. After several years of unsuccessful nominations, he was finally selected for enshrinement in the Pro Football Hall of Fame in Canton, Ohio on February 5, 2011. His induction speech was notable for omitting any mention of both Ditka and Chicago defensive coordinator Buddy Ryan.
Dent has had a difficult relationship with Ditka since retirement because of blaming Ditka for the 1985 Bears' inability to repeat as Super Bowl champions.
Dent was also inducted into the Georgia Sports Hall of Fame on February 15, 2008.