Interface modification is an effective and promising route for developing functional electrocatalysts. However, researchers have not created a reliable method to optimize the interfaces of components existing in electrocatalysts, although it is very crucial for the technological development of high-performance electrodes. Here, we develop a strategy aiming at the in situ anchorage of Co9S8 nanoparticles into a nitrogen (N), sulfur (S) co-implanted three-dimensional carbon matrix (Co9S8@NSCM) as a highly active and durable nonprecious metal electrocatalyst for the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) in alkaline medium. This strategy offers an opportunity to optimize the interface interaction and affords high activity for the ORR and OER in terms of low overpotentials and high current intensities. In addition, by confining Co9S8 nanoparticles into a N,S-doped carbon matrix, corrosion and aggregation can be effectively prevented, and thus the catalyst exhibits nearly unfading ORR catalytic performance after 100 000 s testing, a low discharge-charge voltage gap (0.81 V) and a long cycle life (up to 840 cycles) in Zn-air batteries. The present work highlights potentially powerful interface engineering for designing multi-component heterostructures with advanced performances in oxygen electrochemistry and related energy conversion.