Vegesentials was set up in 2012 by Patience and Andrew Mugadu, building on their experience of making fruit and vegetable cocktails for their children and friends.
Waitrose will be the first national retailer to stock the brand, which has been sold by regional supermarket player Booths.
The agency will implement a strategic programme across trade press and social media to increase brand exposure. It also plans to use the expertise of leading nutritionist, Jo Travers, to reinforce the health credentials of the range in both media sectors.
The drinks claim to have less sugar than fruit juice as they contain half-fruit and half-vegetable blends.
Tom Malcolm, head of consumer at Diffusion, said: "Unlike other brands, Vegesentials’ high vegetable to fruit ratio and use of the innovative HPP (high pressure process) means that their offering is unrivalled in terms of freshness, taste and nutritional value."