Herein, we develop an efficient method for cobalt-catalyzed C(sp³)–H bond functionalization to synthesize indole derivatives. The highlight of this protocol is accomplished by sequential C–H activation. This “cobalt/organic oxidant” catalysis involves cheap Co(OAc)₂·4H₂O and ArSO₂NHOR and features mild conditions, low cost, and good functional group tolerance. Substrates containing primary or secondary inert C(sp³)–H bonds were well applied to this strategy. In addition, the isolated dehydrogenation byproduct indicated that the reaction might involve sequential C–H bond activation.