The mountain ecosystems of Oman represent important centres of plant biodiversity within the arid Arabian Peninsula, supporting distinctive vegetation communities, geographically restricted species, and habitats maintained by complex interactions among elevation, precipitation, temperature, and atmospheric moisture. The Al Hajar Mountains of northern Oman and the Dhofar Mountains of southern Oman exhibit contrasting climatic regimes, making them particularly valuable for understanding the ecological consequences of climate change in arid and semi-arid mountain environments. This review critically examines the relationships between climatic variability, plant biodiversity, ecological vulnerability, and conservation priorities across these mountain systems. Particular attention is given to the montane juniper woodlands of the Al Hajar Mountains and the seasonally cloud-affected woodlands of Dhofar. Available evidence indicates that warming, water limitation, and altered moisture availability may threaten vegetation persistence, recruitment, and habitat suitability. However, climate-related pressures frequently interact with grazing, land-use change, habitat fragmentation, and other anthropogenic disturbances, complicating the attribution of observed vegetation changes to climate change alone. The review highlights differences between northern and southern mountain ecosystems, evaluates the strength of existing evidence, and identifies limitations associated with insufficient long-term monitoring, incomplete species distribution records, and limited integration of climate projections with ecological observations. Future conservation efforts should prioritize climate-sensitive habitats, systematic biodiversity monitoring, improved understanding of fog–vegetation interactions, and spatially explicit assessments of species vulnerability. Integrating ecological research with climate modelling and sustainable land management could strengthen biodiversity conservation and ecosystem resilience in Oman's mountain landscapes.