The operation of magnetic devices with a magnetic field or spin current causes high energy consumption. Very low energy consumption can be achieved by using multiferroic thin films, where we can control the magnetization direction by applying an electric field. Good magnetic properties in multiferroic thin films are needed for these magnetic device applications. However, multiferroic thin films generally do not have such good magnetic characteristics, like high saturation magnetization (Ms), perpendicular magnetic anisotropy (PMA, the ratio of coercivity between the alignment of film plane perpendicular and parallel to the applied field (Hc⊥/Hc//)), magneto-optical Kerr rotation angle (Θk) and Curie temperature (Tc). In this research, we have looked into improving magnetic characteristics such as Ms, Hc⊥/Hc//, Θk and Tc in (Bi,L)(Fe,Co)O3(L = Lanthanides) thin films by substituting different lanthanides with cobalt. The highest Ms value of 140 emu/cm3 and large Hc⊥/Hc// ratio of 2.6 were found in (Bi,Nd)(Fe,Co)O3 thin film, and maximum Θk of 0.67° and relatively high Hc⊥/Hc// of 1.6 were found for the (Bi,La)(Fe,Co)O3 thin film. These properties are suitable for magnetic recording devices and optical devices, respectively. A very small coercivity of 0.8 kOe, along with a high Ms value of 110 emu/cm3 and Tc of 450 °C, were observed in the (Bi,Eu)(Fe,Co)O3 thin film. So, the (Bi,Eu)(Fe,Co)O3 thin film is suitable for magnetic sensor applications because of its high sensitivity to magnetic fields. Moreover, the domain size of the above-mentioned thin films was observed in the small nano range, which is suitable for magnetic nano device applications.