The Andaman and Nicobar Islands (ANI) harbour one of the most diverse mangrove ecosystems in the Indian Ocean. They represent a critical biogeographic link between the Indian subcontinent and Southeast Asia. This review synthesises current knowledge on species diversity, distribution, ecological functions, and conservation challenges, with particular emphasis on the impact of the 2004 Indian Ocean earthquake and tsunami. Documented species richness stands at 38 true mangrove species. This is approximately 50% of the global total. This underscores the archipelago's exceptional conservation significance. Although there is extensive legal protection, these ecosystems face threats from coastal development, hydrological modification, sea-level rise, and anthropogenic marine debris (AMD). Recent monitoring studies (2021–2024) confirm ongoing natural colonisation after the devastating tsunami. This reinforces the importance of natural regeneration over artificial planting. The review advocates an ecosystem-based management framework and long-term ecological monitoring to conserve this globally significant and dynamic island mangrove system.