The agency, which was invited by Innocent to join the pitches once they were already underway, triumphed in a shoot-out against Campbell Doyle Dye and Albion.
It is expected that Lowe will be asked to replace the company's current "Your daily fruit" tagline - which was created in-house - once it begins work on the account.
Judy Mitchem, the chief marketing officer for Lowe, said: "Innocent is a very entrepreneurial company with big creative visions, which will play to our strengths as an agency. Ed Morris was hugely involved in the pitch and it is a good win for us."
In April last year, Innocent appointed HHCL/Red Cell to handle its advertising but split from the agency before it had a chance to produce a single campaign.
However, Lowe has been assured that its appointment will be a long-term commitment.
Richard Reed, the Innocent founder and a former DDB adman, handled the Lowe appointment. However, responsibility for the agency relationship will lie with Jamie Mitchell, the recently appointed marketing director.
Innocent launched in 1999 and has established itself as a market-leading brand. It holds 62 per cent of the smoothie market. As well as smoothies, it produces spring water drinks, called Juicy Waters, yoghurt-based drinks, called Thickies, and smoothies for children.
Innocent also recently announced that it is looking for a direct marketing agency, with four agencies expected to pitch for the business.