A novel nanocomposite consisting of 0.3 cobalt lanthanum nanoferrite/0.7 lanthanum perovskite–hematite nanoparticles (CoLa/LaH) and lanthanum perovskite–hematite nanoparticles (LaH) was synthesized using a simple method. The crystallite size was determined by the X-ray diffraction (XRD) pattern, and the particle size was determined using atomic force microscopy (AFM) to demonstrate that the nano-samples had sizes within the nanoscale range. Fourier transform infrared analysis was utilized to ensure that the nano-samples were formed. By adding CoLa nanoferrite to the LaH nanoparticles, an improvement in magnetic measurements was observed. The saturation magnetization of the CoLa/LaH nanocomposite was 1.1-fold larger than that of LaH. Also, the CoLa/LaH coercivity was 1.7-fold higher than in LaH. Furthermore, the CoLa/LaH nanocomposite displayed a higher operating high frequency of 8.9 GHz, which could be used in an X-band super-high microwave frequency, than the LaH nanoparticles. The LaH nanoparticles, on the other hand, demonstrated a high operating frequency of 8.2 GHz, which could be used in the C-band super-high microwave frequency. No activity was observed for the investigated samples against the tested microorganisms, which was unexpected behavior. Therefore, the investigated nano-samples are interesting for being applied in magnetic targeting and separators, in particular the CoLa/LaH nanocomposite.