This work reported a facile synthesis of porous carbons from the silica-rich rice husk biochar via a ball-milling-assisted KOH activation for sorption of tar compounds and volatile organic compounds (VOCs) (i.e., toluene, phenol). The textural properties of activated biochars can be greatly influenced by the mass ratio of KOH and biochar. The high-performance biochar with a large specific surface area (S-BET: 1818 m(2)/g) was produced as the mass ratio was 3. This activated biochar exhibited a hierarchically meso-microporous structure, which benefited for the adsorption process. Particularly, it had long breakthrough time of 2784 min and high adsorption capacity of 264 mg/g for toluene, while it had short breakthrough time of 724 min and low adsorption capacity of 6.53 mg/g for phenol. Significantly, the mixed VOCs of toluene and phenol can be effectively adsorbed. Further, thermal desorption will be an alternative route for regeneration of waste activated biochar.