This study presents a comprehensive multi-temporal Land Use and Land Cover (LULC) analysis of coastal mangrove regions in India, Bangladesh, Pakistan, and Sri Lanka, spanning three decades from 1994 to 2024. Employing supervised classification techniques with the maximum likelihood algorithm in ERDAS IMAGINE 2014, Landsat satellite imagery was systematically analysed across four decadal intervals to map six dominant LULC classes: Mangrove, Other Vegetation, Bare Earth and Sand Deposit, Agricultural Land, Salt Pan and Aquafarm, and Waterbodies. The study area delineation was standardized using buffer zone approaches, including the Mangrove Influence Zone (MIZ) and Ecologically Critical Area (ECA), to capture anthropogenic impacts along mangrove fringes. The findings reveal divergent trajectories across countries-India demonstrating recent mangrove recovery (2014-2024) alongside agricultural expansion (24.30% by 2024), Bangladesh experiencing cyclical mangrove fluctuations with substantial aquaculture proliferation (13.98% by 2024) and significant mangrove decline (31.61% by 2024), Pakistan showing sustained mangrove contraction (20.48% by 2024) and bare earth conversion to agriculture (10.75% by 2024), and Sri Lanka exhibiting rapid agricultural intensification (37.60% by 2024) at the expense of mangrove cover (26.05% by 2024). Transformation matrices quantified precise land cover transitions, revealing that bare earth and sand deposits systematically converted to agricultural land and vegetation across all countries, waterbodies remained relatively stable, and mangrove dynamics varied significantly- India gained 1.08% mangrove loss between 2014-2024, Bangladesh lost 5.13%, Pakistan lost 5.52%, and Sri Lanka lost 3.55% during the same period. The spatio-temporal dynamics documented provide essential empirical foundations for modelling policy interventions, identifying gaps in coastal land management frameworks, spatially targeting conservation zones, and regulating land conversion activities with evidence-based zoning regulations. These geospatial datasets transform abstract policy objectives into spatially explicit, measurable actions, enabling adaptive management strategies that respond to ground realities, close implementation gaps between policy formulation and execution, and ensure sustainable coastal development trajectories aligned with both economic aspirations and ecological imperatives across the South Asian coastal belt. The study underscores the urgent need for transboundary collaboration, strengthened enforcement mechanisms, sustained monitoring through multi-temporal satellite imagery, and climate-responsive land-use planning to safeguard South Asia’s coastal mangrove ecosystems for future generations while supporting sustainable development pathways for coastal communities.