International companies are more and more seeking to act proactively by proposing In-Country Value (ICV) strategies to create sustainable local values in the host countries in which they carry out projects. Still, such sustainable local values are complex to identify because they are often indirectly related to their own value chains, project activities, and outcomes. There are, therefore, both theoretical and industrial needs to model and estimate sustainable values brought by complex projects in host countries, considering direct and indirect effects. In this paper, a systems thinking-based approach combined with a frequency analysis first permitted to build up a model of the sustainable values created by the project in a host country. Then, after underlining the complexity of such a model, a Domain Mapping Matrix (DMM) approach was proposed to help build a process to estimate project impacts in terms of ICV creation. An application to a case study built up with an industrial practitioner (an oil and gas company) permitted to test and validate the overall model and approach. It notably showed how such a model permitted to facilitate discussions among stakeholders and laid the foundations of ICV creation-oriented decision-making processes.