He replaces former vice-president marketing Michele Oliver, who was promoted last month to global corporate brand and purpose director.
Cavanaugh was previously senior brand director in the US, responsible for four brands: Dove (known as Galaxy in the UK), Twix, Maltesers and Goodness Knows.
Mars said he has begun transitioning to his new role, and will relocate to London in July. He will report to David Manzini, general manager at Mars Wrigley Confectionery UK.
The news comes a week after Chris Rodi, previously marketing director for Mars Chocolate Bitesize, was appointed as marketing director at Mars Petcare.