The week-long festival, which kicks off on 20 June, will be the subject of regular live reports, market analysis and interviews from 22 June.
The focal point will be special coverage in an extended version of its daily Power Lunch Europe programme.
In exchange, CNBC branding will appear on banners at the event, and its programme will be broadcast on plasma screens around the Palais du Festivals.
Rick Cotton, the president and managing director of CNBC Europe, explained: "Many of the most prominent figures from within the advertising industry will be in Cannes, using the festival to make announcements and comments about one of the bellwether business sectors in the global economy. As such, the festival is a natural magnet and focus point for our audience and we are delighted to be the official broadcast partner."
The deal was struck by CNBC, which approached the festival organisers without an intermediary.
Roger Hatchuel, the festival chairman, said: "It is particularly good to have this coverage this year as it is the first time we have so many clients, as well as all the chairmen of the top agency networks, coming to Cannes."
He added: "We are delighted to have, for the first time, an official broadcaster and we welcome CNBC Europe as our partner."