New directions in modern industry are creating distributed virtual enterprises and pushing companies towards service-enhanced products. Both trends converge when a Virtual Manufacturing Enterprise (VME) is created to provide product-service solutions. At the same time, sustainability is a crucial aspect for industrial networks. This paper proposes a methodology to assess the sustainability of Product-Service Systems (PSS) in a VME by modelling an integrated lifecycle, defining impact categories and KPIs, and evaluating all the partners’ contributions. The method allows easily comparing PSS design alternatives to each other or with traditional products. The industrial case study is represented by a “washing as a service” solution proposed by a worldwide VME. Sustainability assessment is useful to highlight the service benefits as well as the critical phases, and to support VME decision-making.