The diffusion of the culture of sustainability and circular economy increasingly pushes companies to adopt green strategies and integrate circular business models in the corporate agenda. It assumes higher relevance in the packaging industry because of the growing plastics demand, the increasing awareness of consumers on single-use-products, the low recyclability performance and last but not least, the challenge of urban littering and microplastics dispersion in marine ecosystem. This paper presents the case of a small-medium enterprise that implemented a decision-making process to rethink the design of frozen food packaging in accordance with systemic and life cycle thinking. Eco-design and Life Cycle Assessment (LCA) have been simultaneously used to test and validate the redesign process, thus fostering the substitution of the plastic “open and close” cap with a closing method entirely made of cardboard. Results shows how using an integrated decision-making system at the design stage have allowed to get up many benefits at multiple levels, including sustainable and safe supply chain, efficient logistic operations, better recyclability, and lower energy consumption. Moreover, even if it cannot be assessed by the existing tools, the solution provides a strong contribution to the reduction in the consumption of plastics and the prevention of marine pollution.