Core–shell structured mesoporous materials have received great interest for various applications. However, it remains a great challenge to coat mesoporous carbon shells with large accessible pores and short tubular channels due to the difficulty in controlling the interfacial interactions during the co-assembly process. Herein, uniform carbon nanotubes@mesoporous N-doped carbon (CNTs@mesoNC) core–shell structured nanofibers are synthesized by a molecule-mediated interfacial co-assembly strategy. The interaction between F127 and polydopamine can be well mediated by 1,3,5-trimethyl benzene molecules, thus enabling the formation of composited micelles and ensuring the interfacial co-assembly on the CNT surface. Such a strategy is very simple and versatile for synthesis of various mesoporous carbon-based core–shell structures. The obtained CNTs@mesoNC nanofibers possess highly conductive CNT cores, ultrathin shell thickness (∼28 nm), perpendicular mesopores (∼6.9 nm) in the shell, high surface area (∼768 m2 g−1), and abundant N-doping sites (6.9 at%), which distinguish them from bulk mesoporous carbons with small pore sizes. As a result, the nanofibers exhibit superior electrocatalytic performance toward the oxygen reduction reaction in alkaline media. This method paves a way to design functional core–shell materials with uniform mesoporous carbon shells for potential applications in adsorption, catalysis and energy fields.