The 46-year-old singer hired Quebecor executive Aldo Giampaolo this week after husband Rene Angelil decided to step down. Angelil, 72, discovered Dion at age 12, and had been her manager since 1980. The two developed a romantic relationship, and have been married since 1994.
Giampaolo has been made CEO of Feeling Productions, the management company owned by Dion and Angelil that oversees the singer's career. Angelil will remain as chairman until the new manager moves to Las Vegas and takes control of the company in August.
"Considering our longstanding friendship, our mutual respect and our past collaborations, this was a logical step for all of us," Angelil said in a statement.
"I am extremely touched and honored to be offered this new challenge," Giampaolo said separately. "I see it as a continuation of the close working relationship that Rene and I have enjoyed for the past 25 years."
Angelil did not offer an explanation for his departure, but the news comes just a few months after he had a tumor removed from his throat. He was previously diagnosed with throat cancer in 1999.
"I don't want Rene to stress out with work-related issues," Dion said at the time. "I want him to focus on getting back to 100 percent. ... At home we've been spending a lot of quality time with the family. We feel very fortunate that we've been able to get the best care possible and we thank God every day for helping us to get through this ordeal."