This paper presents a humidity sensing based on perovskites nanostructured thin film for improved sensitivity and optical performance. The nickel-doped zinc thin oxide (NZTO) perovskites thin film was used as a sensing material for the humidity sensing application. The NZTO was deposited on borosilicate glass substrates via aerosol-assisted chemical vapour deposition (AACVD) and nickel (Ni) dopant with 2 %mol was added into the precursor solution. The optical performance was investigated by inserting the NZTO into the optical reflection cavity. The cavity comprises NZTO on the glass that placed in a fixed position in front of single-mode fiber (SMF) and SMF was adjusted using x-direction of the 3-axis stage to obtained different cavity lengths. The performance was evaluated from the free-spectral range (FSR) and extinction ratio (ER) of the different cavity lengths. Then, the cavity with an optimized length was placed inside the humidity chamber for sensing applications. The result shows that the optimized cavity length is 100 µm with FSR and ER of 12.05 nm and 7.247 dB. The sensitivity of the humidity sensing is 0.2657 nm/RH% indicates that the NZTO is an excellent candidate for humidity sensing application.