The red-haired beauty, 52, is expected take over the campaigns for a new product called Cellular Renaissance from next year onwards, media reported.
"I'm an actual user of the brand and it's hard not to be. Every modern woman shops everywhere for beauty, but for me it's mostly the airport or the drugstore. It's nice to be promoting something that is accessible to everyone," she said.
The "Game Change" star, who previously touted products for Revlon, joins an impressive roster with L'Oreal that also includes Jennifer Lopez, Beyonce, Eva Longoria, Gwen Stefani, Lea Michele and Diane Kruger.