As a youth, Aucoin played in the 1987 Quebec International Pee-Wee Hockey Tournament with a minor ice hockey team from Gloucester. Aucoin was drafted 117th overall by the Vancouver Canucks in the 1992 NHL Entry Draft, making his NHL debut in 1994–95, playing one game with Vancouver. With the Canucks, Aucoin established himself as a significant offensive threat, specifically on the power play. However, it was not until his fourth full season with the team that this became evident, as he rose from just three goals in 1997–98 to 23 the next season, 18 of which came on the power-play, tying Denis Potvin for the NHL single-season record. In addition to leading all league defencemen in goals and power-play goals in the 1998–99 NHL season, Aucoin also led all defencemen in shorthanded goals and game-winning goals. However, after one-and-a-half seasons, Aucoin's offensive production dropped to the point where he had only 3 goals through 47 games in 2000–01. On February 7, 2001, Aucoin was traded to the Tampa Bay Lightning for goaltender Dan Cloutier. He only played 26 regular-season games for the Lightning before being traded in the off-season with Alexander Kharitonov to the New York Islanders in exchange for Mathieu Biron and a second-round pick in the 2002 NHL Entry Draft. With the Islanders, Aucoin put up the most consistent offensive numbers of his career, including a career-high 33 assists and 44 points in 2003–04, resulting in him being chosen to play in the 2004 NHL All-Star Game for the Eastern Conference. He shared a victory in the hardest shot competition with Sheldon Souray of the Montreal Canadiens with a 102.2 mph blast and scored the first goal of the game in a 6–4 win over the Western Conference. In 2004–05, he played Modo Hockey in the Swedish Elitserien during the NHL lockout. After NHL play resumed, on August 2, 2005, Aucoin signed a four-year contract with the Chicago Blackhawks, eventually being named team captain. However, the first two seasons of his contract were hampered by injuries, and in the off-season prior to the 2007–08 campaign, Aucoin waived his no-trade clause and was sent with a seventh-round draft pick to the Calgary Flames in exchange for defencemen Andrei Zyuzin and Steve Marr. In his first season with Calgary, Aucoin recorded the fifth 30-point season of his career in 2007–08 with 35 points, and recorded his sixth 30-point season in the 2008–09 season with 34 points. In the summer of 2009, Aucoin, as a free agent, signed a contract with the Phoenix Coyotes. He helped the Coyotes win the Pacific Division in 2012, where they advanced to the Western Conference finals. After three seasons with the Coyotes, Aucoin left as a free agent to sign a one-year contract with the Columbus Blue Jackets on July 1, 2012. During the lockout shortened 2012–13 season, Aucoin served as an alternate captain with the Blue Jackets. In 36 games, he totalled just 4 assists, however added a needed veteran presence at the Blueline. In the summer of 2013, he became an unrestricted free agent. On November 19, 2013, Aucoin announced his retirement from professional hockey. He will begin working with the Chicago Blackhawks' young defensive prospects.
