The Republic of Cuba faces a critical energy trilemma characterized by severe reliance on imported fossil fuels and an obsolete electricity generation infrastructure. Addressing this challenge, this study evaluates long-term decarbonization pathways exclusively for Cuba’s electricity sector from 2024 to 2050 using the Low Emissions Analysis Platform (LEAP). To improve methodological transparency, LEAP was configured using 2024 as the base year, with demand projections, generation capacity expansion, storage deployment, fuel-price assumptions, technology costs, and emissions factors represented across three scenarios. The assessment formally defines three structural frameworks: a policy-continuity baseline based on current governmental targets, a flexibility-oriented decarbonization pathway, and a 100 % renewable electricity scenario. Results indicate that while the policy-continuity scenario achieves a 35 % renewable generation share, its reliance on a conventional thermal baseload triggers a late-term emissions rebound, peaking at 12.82 million metric tons of CO₂-eq by mid-century. Conversely, the flexibility-oriented pathway appears to be the most cost-effective option. By capping thermal capacity at 1,500 MW and deploying large-scale energy storage, it reduces emissions by 67 % to 4.21 million metric tons of CO₂-eq and lowers annual production costs by approximately 200 million USD. Furthermore, sensitivity analyses demonstrate this flexible architecture is highly resilient to demand fluctuations. Although the 100 % renewable pathway suggests absolute electricity-sector carbon neutrality is technically achievable, its requirement for a 6,733 MW biomass scale-up introduces major capital and land-use conflicts. Ultimately, this research indicates that deep decarbonization could be an economically advantageous strategy, necessitating a paradigm shift from traditional baseloads toward system flexibility, provided significant external financial barriers can be navigated.