Herein, the geometrical, magnetic, optoelectronic, thermoelectric features of K2LiMoX6 (X = Br, I) have been simulated by DFT. The FP-LAPW approach is employed via Wien2k software. To confirm the thermodynamic and structural stability of the K2LiMoX6 (X = Br, I) compounds, the tolerance factor (τ) and formation enthalpy are calculated. The predicted spin-polarized band structure (BS) and density of states (DOS) display p-type semiconductor character via direct band gap at X-X symmetry points in both spin versions. The ferromagnetic (FM) character was confirmed from magnetic moments (MTot) which are 3.00090, and 3.00014 μB for K2LiMoBr6, and K2LiMoI6, correspondingly. The materials light absorbance was observed in the range of visible to ultraviolet (UV) zone, thereby enhancing their significance for photocell and optoelectronic devices. In addition, both halides exhibit optimal figure of merit (ZT) which make these materials as promising candidates for efficient heat energy conversion technologies. The outcomes of the studied compounds provide a new path for researchers for the applications of spintronic and optical gadgets.