In this work, novel composite multifunctional electrocatalysts, displaying outstanding electrocatalytic capabilities and phenol degradation performance, were successfully synthesized via a facile and controllable electrochemical deposition process, in which nanostructured bimetallic (Co–Ni) molybdates were uniformly deposited onto the surface of stainless steel felt fibers. Co6Ni4Mo@SSF, identified as the superior electrocatalyst with the optimal molar proportion (Co/Ni = 6/4), possessed an amorphous multimetallic structure that was uniformly distributed, offering abundant active sites and excellent structural stability. Notably, Co6Ni4Mo@SSF demonstrated exceptional bifunctional activity toward the HER and OER while enabling efficient phenol degradation during overall water splitting. In KOH electrolyte containing phenol (20 mg L−1), the overpotentials at 100 mA cm−2 were 330.5 mV (HER) and 229.0 mV (OER), with corresponding Tafel slopes of 46.1 and 44.9 mV dec−1, respectively. Both reactions maintained stable operation for 30 h, with performance comparable to that in pure KOH. Moreover, overall water splitting operated stably at 1.789 V for 30 h, while phenol degradation, following first-order kinetics, was nearly completed within 180 min. After 30 h of continuous operation, the Co6Ni4Mo@SSF electrode retained its elemental composition and nanostructured morphology. The remarkable catalytic activity and phenol degradation capability were attributed to the synergistic interactions among the Co, Ni, and Mo active centers in the Co6Ni4Mo@SSF electrode, coupled with the abundance of exposed active sites derived from the distinct morphological reconstruction from nanoparticles to nanosheets during the overall water splitting process. This work offers a novel strategy for developing highly efficient multifunctional electrocatalysts with considerable promise for practical applications in sustainable energy conversion and environmental remediation.