An in situ coupling approach is developed to create a new highly efficient and durable cobalt‐based electrocatalyst for the oxygen evolution reaction (OER). Using a novel cyclotetramerization, a task‐specific bimetallic phthalocyanine‐based nanoporous organic framework is successfully built as a precursor for the carbonization synthesis of a nonprecious OER electrocatalyst. The resultant material exhibits an excellent OER activity with a low overpotential of 280 mV at a current density of 10 mA cm⁻² and high durability in an alkaline medium. This impressive result ranks among the best from known Co‐based OER catalysts under the same conditions. The simultaneous installation of multiple diverse cobalt‐based active sites, including FeCo alloys and Co₄N nanoparticles, plays a critical role in achieving this promising OER performance. This innovative approach not only enables high‐performance OER activity to be achieved but simultaneously provides a means to control the surface features, thereby tuning the catalytic property of the material.