Sonia Constant is a French perfumer who built her career inside Givaudan, one of the world's largest fragrance and flavor houses. She trained at ISIPCA before completing Givaudan's own in-house perfumery school, and has credited mentors there including Dominique Ropion, Francis Kurkdjian, Olivier Pescheux and Christine Nagel (who is also her sister-in-law) for shaping her approach to formula-writing and accord construction. She went on to join Givaudan's Fine Fragrance Creation team and has since risen to senior/master perfumer, working for the house for more than two decades.

As a Givaudan perfumer she has composed for a long list of prestige fashion and beauty brands, most visibly Narciso Rodriguez's musk-forward 'For Her' fragrances (Fleur Musc, Pur Musc, Musc Noir Rose) and Tom Ford's Ombre Leather and Noir Extrême, alongside work for Mugler, Jimmy Choo, Jean Paul Gaultier, Guerlain, Marc Jacobs and Carner Barcelona (Cuirs). Across these projects she is closely associated with musk, ambroxan, cashmeran, vanilla, orris and orange-flower-forward compositions, and describes a minimalist working method built around paring formulas back rather than layering them up.

In 2017 she co-founded her own niche house, Ella K Parfums, with her husband, also a perfumer, as an outlet for a more personal, travel-inspired style of storytelling built around places she has visited and scents she has captured on those trips. The brand's fragrances, including Camelia K and the Collection K, have won recognition from bodies such as The Fragrance Foundation UK, the Golden/Global Osmanthus Awards in China, Germany's Duftstars and Italy's Accademia del Profumo. She continues to split her creative work between large-scale commercial commissions at Givaudan — including Narciso Rodriguez's 2025 For Her Eau de Parfum Intense, developed with the help of a digital ingredient-pairing tool — and the more intimate perfumes released under her own name.