Perovskite solar cells (PSCs) based on methylammonium lead mixed halide (CH₃NH₃PbI_3-xCl_x) are highly promising for next generation photovoltaic technology owing to their low-cost facile fabrication and superior performance. The power conversion efficiency (PCE) and stability of PSCs are immensely influenced by the crystallinity, homogeneity, uniformity, and defect density of the perovskite films. This work highlights an efficient solution processing route utilizing Chlorobenzene (CB) as an antisolvent during the thin film growth process. It is demonstrated that the planar perovskite film prepared by the CB-modified method yields a homogeneous deposition with a significant reduction in pin holes and defect density. Inverted planar heterojunction PSCs fabricated by this method exhibit a higher open circuit voltage (V_oc) and reduced nonradiative recombination as compared to that obtained in PSCs prepared without CB. The improved film quality results in a huge enhancement of nearly 40% in the PCE. In addition, a significant reduction in the charge carrier’s transferresistance from 2442 to 550 Ω was observed while the defect density was suppressed from 24.6 x 10¹⁶ to 11.1 x 10¹⁶ cm^–3. These CB-modified PSCs also exhibit improved stability in the ambient conditions. This approach would pave the way for the fabrication of low-temperature processed inverted planar PSCs with improved performance.