<p>Although most soil microorganisms exist in a dormant state, the extent, causes and implications of this dormancy for global soil carbon cycling and accrual remain uncertain. An emerging paradigm suggests that energy limitation is the dominant factor causing microbial dormancy in soils, constraining microbial growth and turnover, necromass formation and carbon accrual. Here we applied scaling laws linking microbial energy utilization to biomass growth and maintenance, providing a framework to quantify coupled carbon–energy fluxes. By integrating a microbial-process explicit model, global-scale datasets and deep learning, we estimated that microorganisms can obtain 37 ± 22 MJ m⁻² yr⁻¹ of energy by oxidizing available organic carbon in topsoil (0–30 cm). This energy amount can support at most 8 ± 6% of the total microorganisms under a growth state or 61 ± 57% under a maintenance state, leaving at least two-fifths of the microorganisms in dormancy. Despite variations in land use and climate, the global mean microbial energy use efficiency (0.22 ± 0.02) is 17% lower than carbon use efficiency (0.27 ± 0.04). These findings reveal a ubiquitous rule of energy limitation for microbial activity and consequently for necromass production—the main source of soil organic carbon accrual.</p>