Reductions in carbon emissions have been a focus of the power sector. However, the sector itself is vulnerable to the impacts of global warming. Extreme weather events and gradual changes in climate variables can affect the reliability, cost, and environmental impacts of the energy supply. This paper analyzed the interplay between CO2 mitigation attempts and adaptations to climate change in the power sector using the Long-range Energy Alternative Planning System (LEAP) model. This paper presented a novel methodology to integrate both CO2 mitigation goals and the impacts of climate change into simulations of a power system expansion. The impacts on electricity supply and demand were quantified, based on historical climate-related impacts revealed during fieldwork and existing literature. The quantified effects, together with climate mitigation targets, were then integrated into the LEAP modeling architecture. The results showed a substantial alteration in technology composition and an increase in installed capacities driven by the joint climate mitigation–adaptation efforts when compared with the scenario without mitigation and adaptation (reference). Furthermore, an increase in CO2 emissions was observed under the mitigation-adaptation scenario compared with the mitigation only scenario, indicating that the power sector’s adaptations for climate change are likely to hinder CO2 mitigation efforts. Therefore, a nexus between mitigation and adaptation should be exploited in the policy development for a low-carbon and climate-resilient power system.