Halle, 46, walked the red carpet with her man, 47, who was the honorary president of the event.
Wearing a sheer black Tramando dress and Brian Atwood shoes, Halle beamed as the daddy-to-be posed for photos with his hands on her belly.
And it seems the 5-months-pregnant star is loving transparent maternity looks.
Only two days prior to her appearance in France, Halle picked up groceries in Beverly Hills wearing a see-through black shirt that showed of her growing baby bump and lacy black bra underneath. The X-Men star paired the top with cut-off jean shorts, sandals and shades.
While the daddy-to-be is originally from France, he revealed that his son with Halle will “be an American,” while he remains French.
“I remain a Frenchman in America, but I adapt to American culture,” said the actor, who has lived with Halle in California for the past two years. “I feel good there — but I’m still a foreigner.”
“My son will be an American,” he repeated.