Purpose – The purpose of this paper is to explore the role of a quality management system (QMS) for the assurance and improvement of value in an inter‐organizational business relationship. The study is carried out in the public transportation industry where service provision has been outsourced.Design/methodology/approach – In‐depth interviews are conducted with 26 participants from two organizations involved in an inter‐organizational business relationship. From the interview material, the authors identified the drivers that create value for the inter‐organizational business relationship and for the customers of public transportation. All value drivers are categorized according to the central areas in a QMS.Findings – The results show that internal processes and management responsibility are central areas where value is destroyed. Since service provision has been outsourced, this means that the intended value is never experienced by the customer.Research limitations/implications – The identified value creators and destroyers originate from the suppliers' view and focus on how the different suppliers create value for customers.Practical implications – Managers should acquire knowledge about the value they create or destroy and focus on improving the value‐creation processes. The QMS can be used to assure and improve value creation in an inter‐organizational business relationship.Originality/value – The research sheds light on the difficulties and possibilities in value creation where service provision has been outsourced.