Sacred groves are traditionally protected forest patches conserved by indigenous communities through cultural and religious practices, representing one of the oldest forms of biodiversity conservation. In Karnataka, these groves—locally known as Devarakadus, Kans, and Nagabanas—play a significant role in preserving ecological integrity within the biodiversity-rich landscapes of the Western Ghats. This review synthesizes existing literature on the biodiversity, ecological significance, and conservation value of sacred groves in Karnataka. The analysis highlights that sacred grove function as micro-reserves of biodiversity, harbouring endemic, rare, and medicinal plant species, while also supporting diverse faunal communities. These ecosystems contribute to essential ecosystem services, including soil conservation, water regulation, and microclimate stabilization. The review further emphasizes the critical role of indigenous knowledge systems and socio-religious practices in regulating resource use and ensuring long-term conservation. Despite their importance, sacred groves are increasingly threatened by urbanization, land-use changes, and the erosion of traditional belief systems. The study identifies key research gaps, including limited focus on faunal and microbial diversity, lack of long-term ecological monitoring, and insufficient integration of traditional knowledge with modern scientific approaches. The review underscores the need for interdisciplinary research and policy interventions that integrate indigenous conservation practices with contemporary ecological frameworks. Strengthening community participation and incorporating sacred groves into formal conservation strategies are essential for ensuring their sustainability. Sacred groves thus represent a valuable model for biodiversity conservation, offering important insights into sustainable environmental management in the face of growing ecological challenges