The singer and her husband Rene Angelil christened four-month-old tots Eddy and Nelson at the St. Elizabeth Ann Seton Catholic Church, in a ceremony that featured chanted prayers and songs.
Her representative said of the Melkite Greek Catholic rite: "It was a beautiful, traditional family ceremony."
The boys wore gowns by Baby Dior while their 10-year-old brother, Rene-Charles, was one of their godparents, along with Celine`s sister Linda and Rene`s three oldest children, Patrick, Jean-Pierre and Anne-Marie.
200 friends and family were in attendance, including the doctors who helped Celine, 42, conceive the babies through In Vitro Fertilisation (IVF) and those who treated 69-year-old Rene when he had cancer over 10 years ago.
After the service, Eddy and Nelson napped while the rest of the family celebrated with a reception at nearby Caesars Palace.
Celine is due to start a residency at Caesars Palace on March 15 and recently said she will carry on breastfeeding her sons, despite the gruelling schedule.
When quizzed on what her plans for the boys are once her shows start, Celine said: "I can either go to them or they can come to me - it`s going to be practical, it`s going to be easy since I`m still breastfeeding the babies, so it`s every three hours - for both.
"The show is an hour and 40 minutes. Then I have time to shower and get loose and relax and breastfeed the babies again and then have a bite and go to bed myself."