In this paper, we demonstrate the practicality and feasibility of the flash light-sintering method to fabricate the ceramic material perovskite structure for lanthanum nickel oxide (LaNiO3; LNO) thin films using flash light irradiation equipment. LNO thin films are deposited on an Si wafer and Al2O3 substrate via the chemical solution deposition (CSD) method and sintered by a thermal and flash light-irradiation process with a bottom heater. The properties of flash light-sintered LNO thin films are compared with those of thermally sintered films. The surface morphology, crystal development, and electric conductivity of the LNO thin films are measured by field-emission scanning electron microscope (FE-SEM), X-ray diffraction (XRD), and a four-point probe, respectively. Flash light sintering was accomplished in milliseconds. Through the comparison of thermal sintering and flash light-sintering results, it was confirmed that perovskite LNO thin films deposited by the CSD method can be fabricated by flash light sintering. We show that the flash light sintering method can solve several inherent issues of the conventional thermal sintering method.