He leaves the role with no job to go to and will now serve six months of gardening leave before deciding on his options.
Sources close to Marsden speculated he may be considering a move to the COI, where he has close contacts. However, he would not confirm this.
Marsden said: "It feels like a good time to leave. There is still a great deal I want to do and I am sure that it will be outside the soft drinks category. It just feels like the right time. It is purely coincidental that it is 18 months after the company was floated."
He added that his departure would not affect the brand's existing agency relationships. CHI & Partners' handles advertising and Mindshare works on media for Britvic.
Paul Moody, the chief executive, added: "Andrew is Britvic's longest serving director and has been a key figure in the development of our business. He has achieved a great deal and we wish him every success in his future endeavours."
During his time at Britvic, Marsden developed Robinsons into a Top Ten grocery brand as well as launching product extensions such as J20, Fruit Shoot and Fruit Shoot H2O.