PurposeThe authors analysed fairness as an antecedent of trust to understand how trust building can be actively managed to facilitate collaboration in buyer–supplier relationships.Design/methodology/approachA case study was employed to buyer–supplier relationships of five organic food companies from three different sectors. The research was developed with data collected in 2022 through qualitative research interviews and analysed using a structured content analysis. A practitioner workshop served to complement findings and confirm the interpretation of data by discussing interview results from a managerial perspective.FindingsA conceptual model based on organisational trust and justice theory was developed to examine causal relations between fairness and trust. Findings show that perceived distributional, procedural and interactional fairness mutually interact with the perceived trustworthiness of business partners and that both contribute to building personal, organisational and institutional trust. Qualitative data support the conceptual model and show that trust is a valuable relational resource that affects relationship quality and the willingness to collaborate and to take risks in times of uncertainty.Practical implicationsHigh trust levels developed through positive fairness perceptions can lower risk perceptions whilst increasing the willingness to collaborate in supply chain relationships. This can help deal with market uncertainties.Originality/valueThrough the lens of organisational trust and justice theory, this study extends the literature on collaboration in supply chains by including a comprehensive view on the formation of trust in business-to-business (B2B) relationships.