To improve the pore uniformity and volume of ordered mesoporous carbons produced by soft templating under solvent-free conditions, magnesium nitrate inorganic salt was incorporated into the precursors during the synthesis. The addition of magnesium nitrate in this procedure lowered the melting point of resorcinol, increased the diffusivity of the resorcinol-Pluronic F127 complex, and promoted self-assembly. The entry of Mg species into the core of the micelle of Pluronic F127 resulted in a modification of the pore structure resembling a channel-like hexagonal structure. In addition, the MgO in the pores effectively prevented the shrinkage of the mesopores under high-temperature conditions. Correspondingly, the uniformity and the mesopore volume of the mesoporous carbon obtained were also enhanced. Moreover, when used as electrodes, this ordered mesoporous carbon was able to significantly increase the capacity of electric double-layer capacitors. Thus, the current study proposes a novel method for regulating the structure and distribution of ordered mesoporous carbons.