He was the first major acquisition of new general manager John Ferguson Jr., who took over on Aug. 29.
Terms were not disclosed, but the Sports Network of Canada reported that Nieuwendyk agreed to a one-year contract believed to be worth considerably less than the $5 million he was paid by the New Jersey Devils last season.
The signing came one day after Doug Gilmour announced his retirement.
Nieuwendyk, an unrestricted free agent, totaled 17 goals and 28 assists in 80 games last season in the worst injury-free campaign of his 17-year career. In January, he became the 32nd player in NHL history to reach the 500-goal mark.
Last spring, Nieuwendyk captured his third championship, although he sat out the Stanley Cup Finals because of a torn oblique muscle. He was acquired from the Dallas Stars in March 2002 as part of a four-player trade.
Nieuwendyk, Calgary's second-round pick in the 1985 draft, has 511 goals and 501 assists in 1,113 games, won the Cup with the Flames in '89, the Calder Trophy as rookie of the year in 1988, and a gold medal with Canada at the 2002 Olympics.