Blue carbon ecosystems—comprising mangroves, salt marshes, and seagrass meadows—have emerged as critical natural climate solutions that simultaneously mitigate greenhouse gas emissions and strengthen coastal resilience. In India’s vast deltaic systems, including the Ganga–Brahmaputra–Meghna, Godavari–Krishna, Mahanadi, and Cauvery deltas, these ecosystems act as silent carbon sinks, capturing and locking away organic carbon within anaerobic sediments for centuries. Recent assessments (2019–2024) reveal that mangroves and seagrasses can sequester carbon up to four times faster than tropical rainforests, underscoring their immense mitigation potential. However, escalating pressures from urbanization, aquaculture, and infrastructure expansion have led to significant ecosystem degradation, resulting in the release of stored carbon and the erosion of biodiversity. This chapter examines the ecological functions, policy frameworks, and spatial planning implications of blue carbon ecosystems within India’s deltaic landscapes. It highlights the potential of integrating Nature-Based Solutions (NbS)—including mangrove afforestation, seagrass meadow restoration, and salt-marsh buffers—into urban and regional planning to strengthen coastal adaptation strategies. By aligning blue carbon conservation with India’s updated Nationally Determined Contributions (2022) and global Sustainable Development Goals (SDGs), particularly SDG 13 (Climate Action) and SDG 15 (Life on Land), the chapter reframes these ecosystems as living infrastructure essential for climate-resilient development. Ultimately, it calls for a paradigm shift from fragmented conservation toward integrated delta governance, where ecological restoration, spatial design, and policy coherence together sustain both people and planet.