Addressed herein is the catalysis of bimetallic PdxNi1‐x and PdxCo1‐x nanoparticles (NPs) supported on a cryptomelane‐type manganese oxide (K‐OMS‐2) solid for the Suzuki–Miyaura cross‐couplings of phenylboronic acid with various aryl halides. Bimetallic PdxNi1‐x and PdxCo1‐x NPs were prepared by using a conventional one‐step impregnation–reduction method. Among these catalysts with different compositions of Ni and Pd or Co and Pd, the Pd0.2Ni0.8 and Pd0.2Co0.8 catalysts showed the highest activity in the Suzuki–Miyaura cross‐couplings of various aryl halides including iodides, bromides, and even chlorides with phenylboronic acid in ambient air and water under reflux conditions. The Suzuki–Miyaura cross‐coupling reaction proceeded efficiently in the presence of Pd0.2Ni0.8@K‐OMS‐2 and Pd0.2Co0.8@K‐OMS‐2 NPs under the optimized conditions in water. Pd0.2Ni0.8@K‐OMS‐2 and Pd0.2Co0.8@K‐OMS‐2 NPs provided high conversions up to 98% and 99% and turnover frequencies of 11,760 and 11,880 h−1 in the cross‐coupling of phenylboronic acid with 1‐bromo‐4‐nitrobenzene. More importantly, these new supported Pd0.2Ni0.8@K‐OMS‐2 and Pd0.2Co0.8@K‐OMS‐2 NPs were found to be highly durable nanocatalyst throughout the reusability experiments, and they maintain almost their inherent activity after 10th and 5th catalytic cycle, respectively. Bimetallic Pd0.2Ni0.8@K‐OMS‐2 and Pd0.2Co0.8@K‐OMS‐2 NPs were characterized by Fourier transform infrared spectroscopy (FT‐IR), transmission electron microscopy (TEM), scanning electron microscopy with energy dispersive X‐ray (SEM‐EDX), X‐ray diffraction (XRD), X‐ray photoelectron spectroscopy (XPS), and ICAPQ inductively coupled plasma mass spectroscopy (ICP‐MS) analyses.