Greg De Vries played midget hockey with the Cortina Astros in Ontario. In 1989-90 he joined the Aurora Eagles in his first of two Junior B seasons; in 1990-91, he skated for the Stratford Cullitons, a perennial powerhouse in Tier II hockey. In 1991-92, De Vries enrolled at Bowling Green State University and played 24 games as a CCHA freshman. In 1992-93, he returned to Ontario and joined the Niagara Falls Thunder in the OHL. In 62 games that season, he scored 26 points as a rookie and in 1993-94, he improved to 45 points in 64 OHL games. At the end of the season, he signed with the Oilers organization and turned pro with the AHL's Cape Breton Oilers. In 1994-95, De Vries joined the AHL Oilers full-time and scored 24 points. Greg De Vries signed as a free agent with the Edmonton Oilers on March 20, 1994. Less than two years later, he made his NHL debut against the Dallas Stars. On October 1, 1998, De Vries was traded to the Nashville Predators and after just six games with the expansion Predators, was dealt to the Colorado Avalanche. Upon his arrival in Colorado, De Vries had a regular spot in the lineup and was instrumental on the blueline, helping the Avalanche win the Northwest Division title.



In 2000-01, De Vries scored 17 points from the blueline as the Avalanche won the Presidents' Trophy with 52 wins and 118 points, which were both club records. In the playoffs, De Vries strong play in his own zone was instrumental in Colorado's Stanley Cup win in 2001 and continued to play sound defensive hockey, while contributing offensively when counted on. Coming off a career year offensively (6-26-32) with the Avalanche in 2002-03, the New York Rangers signed the former Niagara Falls Thunder rearguard in the summer of 2003 as a free-agent. Upon his arrival in New York, De Vries went on to play 53 games with the Rangers before being dealt at the 2004 trade deadline to the Ottawa Senators for Karel Rachunek and prospect Alexandre Giroux. After only a brief stint with the Sens, De Vries was dealt to the Atlanta Thrashers along with Marian Hossa for budding superstar Dany Heatley in the summer of 2005.