Nowadays, developing simplistic, low-cost, and environment-friendly ways for the synthesis of nanoparticles (NPs) is very attractive, as reported synthesis processes with use of toxic chemicals are particularly complex. In this report, a facile and one-step approach, i.e., the sonofragmentation method, had been applied for the synthesis of FexCo1−x (x = 0.20, 0.40, and 0.80) NPs with enriched saturation magnetization and coercivity. Morphology and structure of the NPs were observed using a scanning electron microscope (SEM) and X-ray diffraction (XRD) respectively. The energy dispersive spectroscopy analysis was used for the confirmation of elemental composition. The crystalline structure of NPs was confirmed from the XRD patterns, and the crystallite size obtained from the powder XRD peak using the Scherrer equation was approximately 24.5 nm. The accumulation of NPs was observed in SEM analysis. Moreover, the magnetic property was characterized using a vibrating sample magnetometer at room temperature. The saturation magnetization (Ms) value was measured from the magnetization (M)-applied field (H) curve and found to be increased from 107 to 153 emu/g (107 to 153 Am2/kg) and the coercivity (Hc) decreased from 128 to 72 Oe (10.18 to 5.53 kA/m) for increasing the iron content in iron-cobalt NPs. Furthermore, the magnetic properties (i.e., Ms and Hc) of synthesized iron-cobalt NPs were compared with those of other methods of synthesis. The overall findings suggest that the present approach is simple, cost-effective, and environmentally safe for the synthesis of NPs.