This study addresses the issue of eliminating Congo red dye from aqueous solutions through green pyrolysis of hybrid iron oxides/graphene-coated iron slag. A novel adsorbent was developed, utilizing cost-effective date fruit-derived graphite and iron slag byproducts. The resulting macroporous structures resemble two-dimensional graphene sheets on an iron slag substrate. Optimal production conditions were determined as pH 12 and 1 g/50 mL slag dosage for 3 h, achieving a remarkable dye removal efficiency of over 95%. Furthermore, a maximum removal percentage of 97% was attained at pH 3 within 60 min, using 0.2 g of adsorbent per 50 mL of solution with an initial dye concentration of 50 mg/L. Sorption data fit well with both the Freundlich and pseudo-second-order models. Increasing the number of composite sorbents in the column resulted in enhanced sorption capacity and prolonged breakthrough time, effectively represented by the belter model. Based on these findings, we recommend the application of this innovative adsorbent for efficient removal of Congo red dye from wastewater.