The reliance on fossil fuels for electricity production in insular regions creates critical environmental, economic, and logistical challenges, particularly for ecologically fragile islands. Transitioning to renewable energy is essential to mitigate these impacts, enhance energy security, and preserve unique ecosystems. This systematic review addresses key research questions: what practical strategies have proven effective in reducing fossil fuel dependency in island contexts, and what barriers hinder their widespread adoption? By applying the PRISMA methodology, this study examines a decade (2014–2024) of research on renewable energy systems, highlighting successful initiatives such as the integration of solar and wind systems in Hawaii, energy storage advancements in La Graciosa, hybrid renewable grids in the Galápagos Islands, and others. Specific barriers include high upfront costs, regulatory challenges, and technical limitations, such as grid instability due to renewable energy intermittency. This review contributes by synthesizing lessons from diverse case studies and identifying innovative approaches like hydrogen storage, predictive control systems, and community-driven renewable projects. The findings offer actionable insights for policymakers and researchers to accelerate the transition towards sustainable energy systems in island environments.