The future technologies belong to the spin-based electronics (called spintronics) which is considered as highly efficient and quick response device with advanced functionalities. In order to develop a functional spintronic device, it is pertinent to control the spin currents and readout of their magnetic states which exemplify the importance of presented study. Herein, physical properties of KNbO3 are engineered via concentration dependent Ni doping with dopant’s concentration of 12.5%, 25%, 50%, and 75%. Ferromagnetic character is obtained along with spin polarized bands and DOS structures. Further analysis of projected DOS reveals the Ni-d based metallic character in spin down channel along with semiconductive nature in spin up version, translating the considered doped systems into half metallic ferromagnetic (HMFM) materials. The computed HM direct gaps are 0.956, 0.957, 1.040 and 0.876 eV for K0.875Ni0.125NbO3, K0.75Ni0.25NbO3, K0.5Ni0.5NbO3, and K0.25Ni0.75NbO3, respectively. The magnetic moment values obtained for K0.875Ni0.125NbO3, K0.75Ni0.25NbO3, K0.5Ni0.5NbO3, and K0.25Ni0.75NbO3, are 1.00153, 1.00003, 1.02449, and 1.04210 μB per formula unit, respectively. The determined magnetic moment values illustrate the ferromagnetism in studied Ni modified KNbO3, perovskites, which is originated from Ni and minor contribution of O ions. Further, optical response of Ni doped KNbO3 is studied which show UV region of light as a strong absorbing region. The presented results predict the suitability of considered material in various optical filters and spintronic devices. [ABSTRACT FROM AUTHOR]