In this study, a Prussian blue analog (PBA)-derived Co/CoTe heterostructure with a unique hierarchical 3D structure is synthesized via a three-step process involving precipitation, reflux-hydrothermal method, and hydrogen treatment. This framework facilitates efficient exposure of the catalytically active sites and fast diffusion of the electrolyte. Additionally, the well-defined metal/semiconductor heterointerfaces lead to an overall electrical conductivity enhancement, and promoted the oxygen evolution reaction (OER) kinetics by lowering the activation energy. The Co/CoTe heterostructure displays a remarkable OER electrocatalytic activity compared to the pure components, indicating a key role of the synergistic effects of Co and CoTe. The best measured OER activity shows an overpotential of 400 mV at a current density of 50 mA cm-2, and a low Tafel slope of 94.1 mV dec-1. Furthermore, aging studies on this material provide reliable evidence of its long-term durability: the OER stability are tested over 50 h in alkaline media. The synthetic strategy reported in this paper provides new insights into the design and preparation of high-performance heterostructured materials of interest in energy-related applications.