•The sustainable supplier selection and order allocation problem is considered.•The issues in establishing long-term buyer-supplier relationships are addressed.•A multi-agent system approach is proposed to address the identified gap.•The applicability of the approach is tested by a real-world case application. Recently, incorporating sustainability into the buyer-supplier sourcing decisions has achieved a considerable amount of attentions among researchers and industrial enterprises who are attempting to move towards sustainable production. Moreover, by investigating further in the buyer-supplier relationships, the literature suggests that proper communication and structured information exchange are important components in establishing a long-term partnership and maintaining such a relationship. Toward this end, a Multi-Agent Systems (MASs) approach is proposed as a mean of automating and facilitating the process of sustainable supplier selection and order allocation (SSS&OA) resulting in a more co-operative partnership. This research shows that financial performance of manufacturing companies adopting environmental and social sustainability in their operations strategy enhanced their competitive advantage that can lead to long-term sourcing relationships for the buyer-supplier dyad. Additionally, it was also shown that applying MASs to the SSS&OA problem can be utilized as an approach to facilitate communications and automate information exchange processes in Supply Chains (SCs) where suppliers and manufacturer are looking to maintain a long-term SC partnership. The applicability of the developed MAS approach and its incorporated sustainable supplier evaluation and order allocation models is demonstrated using an adopted practical scenario from an industrial case study operating in the electronics sector in medical device industry.