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[3] and scored the first goal of the game in a 6–4 win over the Western Conference.

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,[5] 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.