Purpose: To co-create value through dynamic collaborations, enterprises and their suppliers need to orchestrate the integration of complementary resources when providing business services. As such enterprises' strategic decision to apply a plural sourcing strategy to establish dynamic collaborations with their suppliers implies that both in-house and outsourced business services should be bundled into a business services portfolio. However, the antecedents that affect a business services portfolio have rarely conceptually been identified. Design/methodology/approach: Drawing on resource orchestration theory, the authors theoretically developed and empirically validated a business services portfolio conceptual model. The model aims at explaining the critical antecedents to a business services portfolio based on a unique data set, comprising 121 international enterprises with variation in the degree of outsourcing, size, geographies and maturity. Partial least squares structural equation modelling was used to examine the relationships among the antecedents and a business services portfolio. Findings: The findings show that the antecedent, i.e. plural sourcing strategy, modularised business processes and customer orientation have a direct and significant effect on the enterprises' business services portfolio orchestration. The results of the mediation test indicate that modularised business processes fully mediate the relationships between three independent variables with the orchestration of business services portfolio. Originality/value: This study is the first to analyse the impact of plural sourcing strategy, modularised business processes and customer orientation on the business services portfolio orchestration from a plural sourcing context. Additionally, it examines the mediating role of modularised business processes in the relationship between the antecedents and business services portfolio orchestration.