Sacred groves (SGs) play an important role in the conservation of local biodiversity and provide numerous ecosystem services worldwide. We studied how the ecological status of Central Indian SGs contributes to regional tree diversity and carbon (C) storage. We inventoried the trees in fifty-nine SGs of Madhya Pradesh and recorded a total of 109 tree species (90 genera, 40 families). The most species-rich families were Fabaceae, Combretaceae, Malvaceae and Moraceae. The tree density ranged from 75 to 925 individuals ha^-1 (mean: 398 ± 32 individuals ha^-1), while the basal area varied from 2.5 to 69.2 m² ha^-1 (mean: 24.2 ± 1.9 m² ha^-1). The total C stock {tree C + soil organic C (SOC; 0-30 cm)} ranged from 44.7 to 455.4 Mg C ha^-1 (mean: 153.8 ± 9.6 Mg C ha^-1) across the SGs. The studied SGs represented 74.7% of the total tree diversity and contained 33.1% higher total C stock than the forests of the state. Tree C stock was significantly positively correlated with tree basal area (r₅₇ = 0.965, P < 0.0001), distance from the nearest village (r₅₇ = 0.432, P < 0.001) and number of years of existence (r₅₇ = 0.615, P < 0.0001). The present study highlighted the crucial role of the studied SGs in sustaining regional biodiversity and storing significant amounts of C in biomass and soil. Continued conservation efforts and contained anthropogenic interferences are necessary in order to maintain the current role of these SGs as biodiversity and carbon reservoirs of Central India.