Here is the evaluating result on the applicability of the multi-walled carbon nanotube (MWCNT) and α-iron (III) oxide (α-Fe2O3) nanocomposite as a cathode material in dye-sensitized solar cells (DSCs). The morphology and the structure of the MWCNT/α-Fe2O3 nanocomposite have characterized by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and X-ray elemental mapping analysis. Moreover, the electrochemical performance of the nanocomposite has studied toward the activity of Iˉ/I3 ˉ redox couple which represents high current density, low peak-to-peak separation, low charge-transfer resistance, and almost 100% stable response signal. Furthermore, the computational modeling employing the molecular mechanics (MM) and the restricted-Hartree Fock/semiempirical parameterization (RHF/PM6) methods reveals that the highest occupied molecular orbital (HOMO), the lowest unoccupied molecular orbital (LUMO), and the HOMO-LUMO energy gap of the modeled nanocomposite are as −6.88, −3.62, and 3.26 eV, respectively. These properties match with the electronic-level domino of the DSC structure. Finally, the DSC device has fabricated using N719-sensitized TiO2 photoanode and MWCNT/α-Fe2O3 counter electrode, presenting the open-circuit potential, the short-circuit current density, and the power-conversion efficiency of 0.7 V, 20.37 mA cm−2, and 6.0%, respectively. This study successfully approves the potential of the nanocomposite as a cathode material in iodine-based dye-sensitized solar cells.