This study examines the underlying concerns of global warming in the context of a small island developing states and the ensuing action of phasing out coal to keep global temperature rise below 1.5 • C, as stipulated by the Paris Agreement. Coal is amongst the most carbon intensive fuel, therefore transitioning to low-carbon fuels and renewables is necessary to decarbonise the energy system. In this study, a linear least-cost approach is applied to investigate the potential energy mix necessary to replace coal in Mauritius, using the Open-Source Energy Modelling System (OSeMOSYS). The research was initiated following the updated NDC submitted in 2021. The model spans from 2015 to 2040. This study demonstrates the need for even bolder renewable energy investments, like those in solar, wind, waste-to-energy, and biomass technologies, which would cost over 2.5 billion USD to develop but would reduce emissions by over 70% by 2040 and lessen the need for imported fossil fuels and hence decarbonise the electricity system.