Fromation of CdS/g-C3N4/ZnO (CdCN/Z) ternary composites for the water splitting application is reported here. Produced materials were studied for physicochemical, optical, photo-electrochemical (PEC) and photocatalytic pollutant degradation properties. The current density of CdCN/Z exhibited as 7.4 mA/cm(2) which is 26.4, 21.7, 14.25, and 5.92 folds higher than g-C3N4 (CNU), ZnO (Z), CdS, and CNU/Z, respectively. Additionally, the CdCN/Z composite achieved a higher photon-to-hydrogen conversion efficiency of 0.8 %. The finale composite exhibited a effectual degradation of RhB (99 % in 45 min) in water under light and ultrasonication exposure. The coupling of CNU/Z with CdS promoted the optical absorbance in the longer wavelength. This configuration had facilitated the enhanced photogenerated charge carriers separation. The contemporary work validates that the prepared CdCN/Z heterojunction is an auspicious photocatalyst for effectual water splitting as well as photocatalytic elimination of dye pollutants.