Hughes, who spent two years as Mars UK marketing director from 2000, is retiring. He will be replaced by Emma Evison, who was latterly UK food sales director and previously UK food finance director.
Evison's role will be taken by Kerry Foods sales and marketing executive Tristan Butt, who was previously responsible for Richmond and Wall's sausages.
It comes as Mars instigates changes across its European business. Rankin Carroll, general manager at Mars Ice-Cream Europe, is moving to a new management role across the European food division.