Owing to encyclopedic energy crises and ecological concerns, the conversion of solar energy into sustainable value-added fuel products using a reasonable photocatalyst has received a lot of interest. The crucial challenge of the photoreduction of CO₂ into fuel products such as CO and CH₄ is the minor output and poor selectivity. Herein, a novel synthesized schottky-functionalized type-II heterojunction, Ag/CuNb₂O₆/g-C₃N₄ (Ag/CNO/g-CN), is extensively characterized to provide insights regarding its photocatalytic performance in reducing CO₂. More significantly, electron paramagnetic resonance was employed to assist in understanding the inclusion of Schottky-junction and type II heterojunction charge transfer. The CO₂ photoreduction to CO (2.78 μmol g⁻¹h⁻¹) with Ag/CNO/g-CN was 5- and 3-fold higher than single CNO and single g-CN, and the CO₂ photoreduction to CH₄ was 0.15 μmol g⁻¹h⁻¹ under simulated solar irradiation. This enhanced CO₂ photoreduction was attributed to the large surface area and type II heterojunction, which promoted the separation as well as the transformation of photoinduced e⁻/h⁺ pairs and the superior redox ability of charge carriers. The composite's excellent photocatalytic efficiency towards CO₂ was exceptionally enhanced by depositing Ag on CNO/g-CN. This study paves the way for immediate needs to explore the selective conversion of CO₂ into CO and CH₄ via systematic designing and effective schottky-functionalized type-II heterojunction.