Business-to-business (B2B) marketplace eCommerce platforms have grown in number in the last years. While these platforms allow product/service discovery and purchasing, they are limited in terms of integrating transport processes via well-defined B2B interactions. We approach this problem from an holistic view by dividing it into four sub-problems: enriching product and service descriptions with adequate semantic annotations for smooth discovery; integration of product classification taxonomies and standardized supply chain data representations; integration between purchasing and transport processes at procedural and data model levels; and disconnection between eCommerce platforms and legacy information systems of platform users. In this paper, we proposed a solution for each of these problems and presented a unified approach to integrate purchasing and transport phases in B2B marketplace eCommerce platforms. Finally, we validated the proposed approach with a case study in the scope of the NIMBLE research project including integration of eClass and Furniture Sector Taxonomy classification taxonomies into NIMBLE, semantic annotation of products with the information embedded in those taxonomies and a B2B scenario covering purchasing and transport phases of a traditional supply chain.