This paper contributes new knowledge and understanding about the role that Product Passports might play in advancing sustainable business practices towards a Circular Economy. The significance of this research is the proposed universal definition of a Digital Product Passport Ecosystem (DPPE) for international policy, industrial and technical communities. The novelty of this research lies in the systems thinking approach, coupled with systems engineering, to define and model a DPPE as a System of Systems to derive a definition. Stakeholder perspectives and requirements concerning Product Passports were synthesised using data and analysis from the European Commission's (EC) open consultation on the Sustainable Products Initiative (SPI). Nine high-level capabilities of a DPPE have been identified, and each is explored by mapping a list of information requirements discussed within the consultation. It is shown that different Product Passport applications benefit (or detriment) different stakeholder groups. Findings suggest that DPPE solutions must be systemic, providing interoperability across multiple product life cycles, organisations, supply chains, and value chains in order to operate across international borders: thus realising benefits for world (circular) economies and the planet. Furthermore, it is proposed that if stakeholders utilise a universal definition of a DPPE in conjunction with a set of agreed ethical principles to underpin legislation, there would be fewer contradictions and ambiguity between stakeholders regarding the purpose of a Product Passport and the reasons for sharing data. Finally, the authors conclude that more research is needed on incentives for producers to share data and integrate their existing production systems with the broader ecosystem architectures to allow for maximum interoperability with minimal duplication. In addition, future research should determine specific DPP information requirements on a product-by-product basis, along with opportunities that a DPPE will enable towards industrial symbiosis. [Display omitted] • Novel holistic systems approach used to analyse worldviews of Digital Product Passports. • 9 system of system capabilities inherent but needs agreed sustainability principles. • A socio-technical ecosystem requiring values-based design for systemic change. • Needs architecting for legal, organisational, semantic and technical interoperability. • Different Passport applications benefit or detriment different stakeholder groups. [ABSTRACT FROM AUTHOR]