The 37-year-old actress took to Twitter to announce her son's arrival and name, reported Ace Showbiz.
"Welcome to the world! Our beautiful son Raphael Blanc just born at the American hospital of Paris. There are no words to describe the love," she wrote.
George met her French businessman partner for the first time at a BAFTA after-party in 2012 and they have been together ever since.
The actress had announced her pregnancy on the micro-blogging site last August.