The 40-year-old center will be staying with the team as an assistant coach and special assistant to general manager Garth Snow.
He was flanked at Thursday's announcement by Snow and Islanders owner Charles Wang. Also attending the news conference at a hotel behind Nassau Coliseum were family, friends and former teammates such as Bill Guerin.
"I knew the writing was on the wall and it was something I was going to have to face," said Weight, who paused several times during his speech to wipe his eyes, regain his composure and take sips of water. "As sad as it is, I am very excited and fulfilled with my career. You can't have regrets. I just wish I was healthy."
Calling his decision to retire "very difficult and humbling," Weight suspected at the end of the season that his playing days were done, but he took a month to decide.
Weight did not play after Nov. 17, having totaled two goals and seven assists. He played in only 36 games during the 2009-10 season and 53 games the previous season, his first with the Islanders.
In 1,238 NHL games with six teams, Weight had 278 goals and 1,033 points as one of the league's top playmakers. He won a World Cup of Hockey championship for the United States, and was a three-time Olympian — winning a silver medal at the 2002 Salt Lake City Games.
His time with the Islanders made a lasting impression — Weight and his family have relocated from St. Louis to make their permanent home on Long Island.
Weight, a four-time All-Star who ranks sixth in career points among American-born players, will work with NHL Network during the upcoming Stanley Cup finals.
His long career started in New York, with the Rangers in 1991. Weight spent parts of nine seasons with the Edmonton Oilers and became a star there, posting 104 points in 1995-96, including a career-best 79 assists.
After a stay of three-plus seasons with the St. Louis Blues, Weight was dealt to Carolina in January 2006. He helped the Hurricanes win the Stanley Cup that year before returning to St. Louis in the offseason.
Weight was traded again by the Blues in 2007 to Anaheim and then signed with the Islanders the following summer. He joined longtime friend and fellow American star Guerin, who was New York's captain at the time.
The reunion was short as Guerin was traded to Pittsburgh in March 2009 during their first season together. Weight took over with the 'C' on his sweater in the 2009-10 season.
Weight was originally chosen by the Rangers with the 34th pick in the 1990 draft and made his NHL debut in 1991.
He began preparing for his post-playing career last season, spending some games behind the bench alongside coach Jack Capuano as an adviser. Now he will assist during games and in the front office.
"Just the five games last season I stood on the bench helped me immensely," Weight said. "It's going to be an easy transition for me. I'll be at every game and will feed off their energy. I am not worried about the dynamic at all. To assist Garth and learn from Garth, his focus and drive and work ethic is incredible."
Weight has served as a mentor to 2009 No. 1 overall pick John Tavares, the Islanders' franchise player who has spent two seasons in the NHL. Tavares and forward Matt Moulson lived with Weight's family during his rookie season before getting his own place.
"His playing career speaks for itself," Snow said. "Doug's demeanor, his personality, the character of the man, he has a lot to offer our organization and me on different levels. He can be hands on with the players as an assistant coach or with me on personnel decisions."