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Designing an efficient electrocatalyst for facile oxygen reduction reaction (ORR) is essential to achieve higher fuel cell performance. Herein, we demonstrate a simple in situ process to synthesize cobalt sulfide-decorated N and S co-doped mesoporous carbon (Co9S8/N,S-MC) and evaluated its electrocatalytic activity for ORR in alkaline media. Porous carbon has great potential as a support material due to its well-defined porous architecture, which facilitates the mass transport. Here, the Co9S8/N,S-MC electrocatalyst was designed through a soft template route using pluoronic-F127 as a structure-directing agent, phloroglucinol-formaldehyde resin as a carbon source, and thiourea and cobalt acetate as N, S and Co sources, respectively. The combined effects of cobalt sulfide, heteroatoms and the well-defined porous architecture of mesoporous carbon resulted in the excellent ORR performance of the Co9S8/N,S-MC catalyst. Consequently, the optimized Co9S8/N,S-MC catalyst exhibited an onset potential and limiting current density of 0.87 V vs. RHE, and 3.40 mA cm−2, respectively. These values were very close to those of the commercial Pt–C catalyst with only a difference of 50 mV and 80 mA cm−2, but the Co9S8/N,S-MC catalyst also showed a 30 mV higher half-wave potential and excellent long-term stability compared to those of the commercial Pt/C catalyst. These interesting results suggested the good potential application of Co9S8/N,S-MC as ORR electrocatalysts with longer stability in fuel cells. [ABSTRACT FROM AUTHOR]