The campaign marks the latest stage of Unilever's high-profile 'Love/Hate' work, which helped the FMCG company become advertiser of the year at the Cannes advertising festival in 2010.
The new ad positions Marmite as a no-nonsense addition to bland meals.
Created by DDB, the TV ad features Dave the snail and Geoff the frog talking about their dislike of sophisticated cuisine such as escargot and frogs' legs.
The activity will run until the end of September across TV, digital channels and print (exclusively with the London Evening Standard) to direct consumers to a dedicated Facebook page.
A recipe app and competition will launch to coincide with the ads.
The ad for "Marmite Mondays" targets 20- to 30-year-olds with a Marmite-inspired meal to brighten up their start to the week.
Splendid Communications has handled the PR and digital activity for the campaign, while Iris has worked on the ECRM activity. Media planning and buying was handled by Mindshare.
DDB's Jeremy Craigen was the executive creative director. He worked alongside copywriter Patrick McClelland and art director Feargal Balance. The production company was 12Foot6.
Tom Denyard, marketing manager at Unilever, said: "We expect different elements of the campaign, including the Dave and Geoff animations and Marmite Mondays concept, to particularly appeal to our lapsed audience who love the brand, but would welcome more inventive ways to incorporate the product in their every day meals."