Aim: This study examines the potential of Islamic environmental ethics to promote climate action and sustainable development in Northern Nigeria, with particular attention to the roles of mosques and Islamic institutions. Although Islamic teachings provide extensive principles concerning khilāfah (stewardship), amānah (trust), mīzān (balance), iṣlāḥ (reform), and the prohibition of fasād (environmental corruption), these principles remain insufficiently translated into systematic institutional environmental practices. The study therefore explores how Islamic institutions can transform environmental teachings into practical mechanisms for climate awareness, environmental conservation, and community-based sustainable development. Methodology: The study adopts a qualitative integrative literature review and conceptual synthesis. Relevant Qur'anic and Hadith texts, classical Islamic scholarship on environmental ethics and Maqāṣid al-Sharīʿah, contemporary literature on Islam and environmental sustainability, and studies on climate change and sustainable development in Nigeria are critically analysed. Thematic analysis is used to identify Islamic environmental principles, institutional opportunities, implementation challenges, and pathways for translating religious teachings into practical climate action. Results: The findings indicate that mosques and Islamic institutions possess significant but underutilised potential to function as centres of environmental education, ethical mobilisation, community awareness, sustainable resource management, tree planting, waste reduction, water conservation, and climate-resilient livelihoods. However, limited environmental training among religious leaders, weak institutional coordination, inadequate funding, low environmental awareness, and the limited integration of ecological themes into Islamic education constrain this potential. Conclusions/Novelty: The study proposes an Islamic Environmental Stewardship and Climate Action Framework (IESCAF) linking khilāfah, amānah, mīzān, iṣlāḥ, and Maqāṣid al-Sharīʿah with practical institutional climate interventions. The framework reconceptualises mosques and Islamic institutions as active agents of environmental stewardship and sustainable development rather than merely sites of worship and religious instruction, thereby offering a distinctive Islamic contribution to climate governance in Northern Nigeria.