A facile chemical procedure was utilized to produce an effective peroxy-monosulfate (PMS) activator, namely ZnCo2O4/alginate. To enhance the degradation efficiency of Rhodamine B (RhB), a novel response surface methodology (RSM) based on the Box–Behnken Design (BBD) method was employed. Physical and chemical properties of each catalyst (ZnCo2O4 and ZnCo2O4/alginate) were characterized using several techniques, such as FTIR, TGA, XRD, SEM, and TEM. By employing BBD-RSM with a quadratic statistical model and ANOVA analysis, the optimal conditions for RhB decomposition were mathematically determined, based on four parameters including catalyst dose, PMS dose, RhB concentration, and reaction time. The optimal conditions were achieved at a PMS dose of 1 g l−1, a catalyst dose of 1 g l−1, a dye concentration of 25 mg l−1, and a time of 40 min, with a RhB decomposition efficacy of 98%. The ZnCo2O4/alginate catalyst displayed remarkable stability and reusability, as demonstrated by recycling tests. Additionally, quenching tests confirmed that SO4·−/OH· radicals played a crucial role in the RhB decomposition process.