In this research, the synthesis and characterization of a novel catalyst is reported based on the preparation of the Pd complex of (pyridin-2-ylmethyl)dithiocarbamate (PDTC) supported on γ-Fe₂O₃@SiO₂ magnetic nanoparticles (γ-Fe₂O₃@SiO₂–(CH₂)₃–PDTC–Pd). The catalyst is characterized by scanning electron microscopy, transmission electron microscopy, energy-dispersive X-ray spectroscopy, thermogravimetric analysis, Fourier transform infrared spectroscopy, inductively coupled plasma analysis, X-ray powder diffraction, X-ray photoelectron spectroscopy, and vibrating-sample magnetometer measurements. The catalytic performance of γ-Fe₂O₃@SiO₂–(CH₂)₃–PDTC–Pd was evaluated in the Heck/Sonogashira coupling reactions of various aryl halides with various alkenes/phenylacetylene in water. The synthesized nanocatalyst showed a high catalytic activity even in very small amounts (5 mg, less than 0.1 mol%), was easily separated using magnetic decantation and was reused for ten cycles without any appreciable loss of its reactivity.