The Big Lunch, which is supported by the Big Lottery Fund and partnered by Asda and Halifax, has been running annually across the UK for the past five years.
The event aims to bring people together to eat lunch and develop new friendships in their local community.
The Red Consultancy's brief is to generate national earned media coverage to encourage communities to get involved in next year’s get-together in June. The brief also involves promoting the societal benefits The Big Lunch provides.
Managing director of consumer (life) at The Red Consultancy, Emily Morgan, said: "We’ve been keen to work with Eden for many years and presented an ambitious communications strategy to boost awareness and participation. We’ll be creating new angles and arresting content to bring home to media and influencers just how important it is to build community spirit in Britain today."
The agency will report to Eden Project executive director Peter Stewart.
Stewart said: "As well as strong creative thinking The Red Consultancy showed a depth of understanding of The Big Lunch and its aims. We are confident it will drive awareness and participation in The Big Lunch as we move towards the seventh annual event on Sunday 7 June 2015."