Local hyperthermia is gaining considerable interest due to its promising antitumor effects. In this context, dual magneto-photothermal cancer therapy holds great promise. For this purpose, the use of nanomaterials has been proposed. Therefore, the aim of this research is to develop a dual magneto-photothermal agent consisting of polydopamine-coated nonspherical magnetic nanoclusters. The physicochemical characterization of the nanoclusters was performed by electron microscopy, electron dispersive X-ray, dynamic light scattering, electrophoretic mobility, thermogravimetric analysis, and Fourier transform infrared spectroscopy. The biocompatibility of the nanoclusters was evaluated using human skin M1 fibroblasts. The potential of the nanoclusters as dual magneto-photothermal agents was investigated by applying an alternating magnetic field (18 kA/m and 165 kHz) and/or NIR laser (850 nm, 0.75 W/cm). Nanoclusters showed a size of 350 nm consisting of nonspherical magnetic particles of 11 nm completely coated with polydopamine. In addition, they were superparamagnetic and did not significantly affect cell viability at concentrations below 200 µg/mL. Finally, the SAR values obtained for the nanoclusters demonstrated their suitability for magnetotherapy and phototherapy (71 and 41 W/g, respectively), with a synergistic effect when used together (176 W/g). Thus, this work has successfully developed polymeric-coated magnetic nanoclusters with the potential for dual magneto-photothermal cancer therapy.