The decision underlines the company's aim to boost promotional activity across Europe to attain a greater share of markets, including the UK.
Of Bel's portfolio of products, half are marketed in the UK: Babybel, The Laughing Cow, Leerdammer and Port Salut.
Saatchi & Saatchi Europe won the business following a pitch against Young & Rubicam, Leo Burnett and Ogilvy & Mather. Saatchis already works on Babybel in Europe.
Advertising for The Laughing Cow is to remain with Leo Burnett in the UK, the Czech Republic and France. But Saatchis is thought likely to pick up the business by the end of the year. Bel is also likely to consolidate its advertising business in other international regions into Saatchis.
In November, Bel hired Campbell Soup Company's marketing director for France, Bernard Rubenstein, as chief marketing officer.