Mobility-as-a-Service (MaaS) offers consumers access to multiple transport modes and services, owned and/or operated by different mobility service providers, through an integrated digital platform for planning, booking and payment. The platform provider needs to negotiate independent deals with different transport operators. Consequently, the success of any MaaS platform will depend on the platform provider’s ability to persuade as many operators as possible to join their platform. This study examines the commercial value proposition of MaaS from the perspective of existing transport operators. We find that MaaS could help strengthen complementary relationships between services, offer operators access to newer customers and larger markets, and help them manage their assets more efficiently. However, integration with substitutive services could undermine operators’ profitability. Moreover, similar benefits could be realised through other information and communication technologies without requiring integration with other services. Consequently, if left to the market, integration between operators is likely to be piecemeal and ad-hoc, and may strengthen monopolistic power of some operators. This, alongside the opportunities that MaaS presents to help achieve broader societal goals, calls for an active role for governments in the development, operation and regulation of MaaS to deliver on the vision of a fully integrated transport system. Refereed/Peer-reviewed