The taffeta blue dress featured two of Mirren's favorite styles: an off-the-shoulder design and a plunging neckline. Another standout feature of the gown, which E! News reported was designed by Del Core, was the wraparound train.
Just like her 2019 Cannes Film Festival outing, the actor took her daring style up a notch by coordinating the color of her gown with her hair, which she kept in a curled updo.
Mirren, who is the face of L'Oreal, also carried a black fan printed with the brand's slogan "#WorthIt."
Speaking to British Vogue ahead of the appearance, Mirren spoke candidly about how it took time for her to be comfortable on the Cannes Film Festival red carpet.
"The very first time I came to Cannes was so intimidating and terrifying and overwhelming," she said. "Now I can kind of laugh at it and enjoy it. I see it as a performance."
What made her more accustomed to the experience was dressing the part "You must have a dress that fits you," she added. Ideally a dress that's comfortable, but that's rather idealistic because so many of these dresses are not comfortable, but they look amazing."