The 42-year-old singer's personal doctors were expected to announce the happy news at a press conference at St Mary's Medical Centre, West Palm Beach, later that day.
Dion, who is mum to nine-year-old Rene Charles, had been scheduled to undergo a Caesarean section on Friday but was admitted to the medical centre a week early after showing signs of going into labour.
At the time, she had been pregnant for just 33 weeks.
After a week of bed rest, the songbird was reportedly wheeled into an operating room at about 12.30pm to deliver the twins - conceived via IVF treatment - by C-section.
Dion, who lives at an ultra-exclusive Jupiter estate near to the hospital, is married to her husband and manager Rene Angelil.
Her personal doctors, Ron Ackerman and Ruel Stoessel, were preparing a statement to be released at 5pm (EST) on Saturday, according to the Palm Beach Post.
The performer's presence at the hospital has sparked controversy after it emerged that another pregnant woman was moved from her room in order to make way for the Canadian diva's early arrival.