<p>Mangroves thrive under extreme environmental conditions, including high salinity, temperature stress, and nutrient limitation, yet the biochemical mechanisms underlying this resilience remain poorly resolved. Here, we conducted a metabolomic analysis of <i>Avicennia marina</i> populations from environmentally contrasting arid and semi-arid coastal regions, comparing populations from the Red Sea, the Arabian Gulf, and Western Australia. Using an integrated multiplatform approach based on proton nuclear magnetic resonance, gas chromatography–mass spectrometry, and liquid chromatography–tandem mass spectrometry, we identified distinct region-specific metabolic profiles. Osmoprotectant compounds varied markedly among regions, with proline concentrations approximately 29-fold higher in Western Australian samples than in Red Sea populations, while Arabian Gulf samples showed intermediate levels. Trehalose and glycerol exhibited similar trends, indicating enhanced osmotic adjustment capacity in Western Australia. In contrast, Red Sea samples showed higher relative abundance of polysaccharides and sulfur-containing metabolites, consistent with adaptation to nutrient limitation and extreme salinity, whereas Arabian Gulf populations displayed mixed metabolic signatures reflecting combined natural and anthropogenic stressors. Multivariate analyses demonstrated clear separation among regions, indicating strong environmental control over metabolite composition. These findings show that <i>Avicennia marina</i> exhibits pronounced biochemical plasticity, with region-specific metabolic reprogramming supporting adaptation to contrasting environmental conditions. This study highlights the novelty of integrating multiplatform metabolomics to resolve ecological adaptation across environmentally contrasting coastal ecoregions. and provides a quantitative framework for understanding mangrove resilience under changing environmental conditions.</p>