This paper is meant to presents a concrete methodology to integrate the vendor rating into a Request for Quotation process carried out in a sharing economy context where MaaS digital platforms are exploited. After an analysis of the current state of the art of sustainable decision making into vendors’ selection and simplified LCA techniques, the different steps of the methodology are in depth illustrated: the Resource instantiation, the Sustainability Suppliers Ranking and the Quotation-specific impacts calculation. The methodology deployment in the manufacturing context is then described, focusing on the resource instantiation phase that allows a rapid, but rigorous environmental characterization of suppliers offer. The described path, developed and tested in the MANUSQUARE EU project, could be easily adapted to other digital platforms and further extended to different industrial sectors.