In 2019, Haenel appeared in three films which played at the Cannes Film Festival: Quentin Dupieux's "Deerskin", Aude Léa Rapin's "Heroes Don't Die", and Céline Sciamma's "Portrait of a Lady on Fire". In "Portrait of a Lady on Fire", Haenel portrayed Héloïse, a young aristocrat in 18th-century Brittany who is to be married off to a nobleman from Milan. "The New Yorker"'s Richard Brody took note of her chemistry with co-star Noémie Merlant and complimented the actresses for being "relentlessly graceful, endowed with physical aplomb, contemplative insight, and strong emotion". A. O. Scott of "The New York Times" considered Haenel's performance worthy of an Oscar nomination for Best Actress, and Bilge Ebiri of "Vulture" described the climax of the film (which features Haenel) as "one of the finest pieces of acting and one of the most moving images I’ve seen in eons." Haenel was nominated for the César Award for Best Actress for her performance, her seventh César nomination.