Mathieu, who will start on 1 April, will report directly to Keith Weed, chief marketing and communications officer at Unilever, and will be responsible for a "step-change" in the marketing of the Unilever brand.
His role is expected to be instrumental in Unilever's ambition of doubling the size of the business while reducing its environmental impact.
Mathieu has previously held senior marketing roles at Coca-Cola, where he developed the 'Coke side of life' campaign, and launched Coke Zero into 50 markets.
Mathieu will lead a team of senior marketers comprised of Paul Nevett, vice president Unilever brand, Paula Quazi, vice president future communications, Ros Walker, vice president marketing capability & academy, Jorgen Bartsch, vice president marketing services and Helena Ganczakowski, vice president agency relations.
Keith Weed, chief marketing and communications officer, Unilever, said: "The fact that we have attracted a marketer of Marc's calibre demonstrates just how exciting a place Unilever is to do marketing right now.
"His appointment completes the redesign of my marketing, communications and sustainability leadership team. This talented group of individuals combines the knowledge, experience, and energy to ensure we become a truly exceptional marketing company – consistently."