BMB triumphed against four undisclosed agencies in a competitive pitch overseen by Richard Power, managing director of sales and marketing.
The agency will now get to work on developing marketing design concepts, a digital customer relationship management strategy, as well as producing traditional advertising.
Rocco Forte Hotels runs a network of luxury hotels in a number of European cities including Berlin, Brussels, Frankfurt, Geneva and Rome. It is planning to expand the network to include a five-star hotel in every key city on the continent. It owns Brown's Hotel in London's Mayfair.
The group, which was founded in 1996, recently announced plans to sell its Cardiff and Manchester hotels.
The win comes hot on the heels of BMB picking up global advertising duties for the Diageo-owned Irish whiskey Bushmills following a competitive pitch.
The triumph, which earned BMB a place on the Diageo roster, marked the agency's first global win.
The Bushmills account is estimated to be worth as much as £15m globally, with a UK spend of between £3m and £5m.