The 69-year-old actress, who starred in The Queen, joins the likes of Cheryl Fernandez-Versini, as UK ambassador, and also asked that her campaign shots were left without any retouching or airbrushing.
L’Oreal will be hoping her effect attracts more custom due to the positive and refreshing rapport she has with the British and global consumers.
"I hope I can inspire other women towards greater confidence by making the most of their natural good looks," said Mirren.
L’Oreal is just the latest in a line of beauty brands who are jumping on the mature model movement, as make-up brands Marc Jacobs Beauty and Nars picked Jessica Lange, 65, and Charlotte Rampling, 68, to showcase their latest line of products.