At the University of Washington, Dillon set the team all-time single-season records for rushing yards (1,555 yards) and touchdowns scored (22) in 1996. In the first quarter against San Jose State University, Dillon rushed for 222 yards and caught an 83 yard touchdown pass, setting NCAA records for both rushing yards and all-purpose yards (305) in one quarter. Dillon did not re-enter the game as the Washington Huskies were comfortably ahead 36-0 by the end of the first quarter.
In the 1996 Holiday Bowl vs. Colorado, he rushed for 140 yards and added 2 more touchdowns to his regular-season total of 23 … Scored 5 TDs in 41-21 conquest of UCLA, earning Sports Illustrated National Player of the Week honors as he rushed for 145 yards and added 53 yards in receptions.
In 2003, Dillon only rushed for 541 yards due to injury, which, along with the emergence of Rudi Johnson, precipitated the trade of Corey Dillon to another team. Originally, he appeared to be traded to the Oakland Raiders, but the Raiders were unwilling to sacrifice a second round draft choice for the aging running back. The New England Patriots, on the other hand, willingly traded a second round pick to give Dillon a second chance on a team with a proven track record. Dillon left the Bengals as the team's all time leading rusher with 8,016 yards, easily surpassing the previous record of 6,447 yards set by James Brooks.
In the 2004 season, Dillon proved himself to be a mature and dedicated team player, putting to rest the negative reputation he may have acquired before arriving in New England. Moreover, Dillon had his best year with 1,635 rushing yards and 12 touchdowns, both career highs, and set a franchise record in the process. The year culminated in a third Super Bowl win for New England, in no small part because of the new running game built around Dillon. Dillon was the top rusher of Super Bowl XXXIX with 75 rushing yards and a touchdown, while also catching 3 passes for 31 yards, giving him 106 total yards. He was also a major factor in the Patriots win over the Indianapolis Colts in New England's first playoff game, rushing for 144 yards and catching 5 passes for 17 yards. Overall, Dillon rushed for a total of 292 yards, caught 9 passes for 53 yards, and scored 2 touchdowns in New England's 3 postseason games.
In 2005, Dillon was once again plagued with injury problems and was not able to duplicate his high stats from 2004. He remained a major contributor for the team, rushing for 733 yards and 12 touchdowns in 12 games. Dillon was also used more frequently during this season as a pass receiver, with 23 receptions for 193 yards and a touchdown, which was more receiving yards then he had gained in his past 2 seasons combined.
In the 2006 season, Dillon began sharing the team's rushing duties with rookie running back Laurence Maroney. Even so, he still had a more productive season than in 2005, finishing the year with 812 rushing yards and a career high 13 touchdowns. His 13 touchdowns ranked him 3rd in the NFL in rushing touchdowns, and tied him with Terrell Owens for 7th in total touchdowns.
On March 2, 2007, the first day of free agency, Dillon was released by the Patriots.
As of the beginning of the 2007 NFL preseason, Dillon has not signed with a team and according to those who are close to his camp, he is seriously considering retiring from the NFL and spending more time with loved ones. In mid-August there were rumors that Dillon might rejoin his original team, the Cincinnati Bengals, due to their loss of backup runningback Kenny Irons to season-ending knee surgery. Bengals coach Marvin Lewis quickly struck down that rumor.
On August 5, 2007, Dillon told the Boston Globe that he will not play football again and will retire from his NFL career.
On October 1, 2007, the press reported that the Tampa Bay Buccaneers have expressed interest in Corey returning to the NFL for play for them, and that Corey has stated he is not interested
On November 2, 2007 Dillon admitted to considering a coming back with the Patriots with the season-ending injury to RB Sammy Morris
Ultimately, however, he did not re-join the Patriots that season.
