Speculation over Bruni's pregnancy erupted in May when she cancelled a scheduled appearance to promote Midnight in Paris at the Cannes Film Festival.
Her father-in-law Pal fueled the rumours a week later when he told a German newspaper that he was "looking forward to [meeting his] grandkid".
Former model Bruni finally confirmed reports that she and Sarkozy are expecting an addition to their family in an interview with Nice-Matin, wherein she described the pregnancy as an "unexpected and unhoped for happiness".
When questioned about the sex of the child, the French First Lady replied: "That I do not know myself."
No due date has yet been confirmed, but many French publications have suggested the child will be born in October.
Bruni also revealed that she'd chosen to hide the news from the public for so long out of a desire to protect her family's privacy.
Sarkozy and Bruni met in 2007 and married several months later in a ceremony held at Élysée Palace in Paris.
Bruni is already the mother to a young son Aurélien, whom she had during her relationship with philosophy professor Raphäel Enthoven.
Watch Carla Bruni perform 'Those Dancing Days Are Gone' below: