The catalyst’s photocatalytic activity under sunlight was tested using graphene oxide (GO) from plant cellulose waste and modified by ZnO nanomaterial. The absorbance of the dye’s solution (Rhodamine 6G) was recorded as λmax = 555 nm at regular time intervals. The degradation kinetics of rhodamine was evaluated by applying first-order integrated rate expression, kt = −ln (C/C0). The half-life (t1/2), the rate constant (k), and the time constant τ (Tau) have been obtained by the above rate expression. The rate constant of the reactions carried out with the different materials was calculated and the values obtained were: k_ZnO =1.574 × 10−2, k_GO =1.01 × 10−2 and k_C-GO-ZnO = 4.7 × 10−3 min−1. The degradation efficiency presented by GO, ZnO and GO-ZnO catalysts was 66.67, 70.84, and 70.07%, respectively. FTIR spectroscopy was used to investigate the interactions between the catalyst and the dye. To the best of our knowledge, waste-derived GO-ZnO has not been previously reported for the photocatalytic degradation of Rhodamine 6G.