The textile industry is one of the major industries contributing to water pollution. The wet processing of textiles involves the usage of a wide variety of chemicals and dyes. This water-intensive process can potentially affect the water bodies by its effluents. The treatment of dye effluents and reusing of the water could be the possible solution to reduce the impact. Adsorption is one of the most common methods used for textile effluent treatment. Various bio-adsorbents are explored to make the adsorption more sustainable. Nigella Sativa (Black cumin) seeds and its oil are having good medicinal value. The seed-waste left after the oil extraction is found to have active components that can be used as an effective bio-adsorbent. The dye removal efficiency of Nigella Sativa seed-waste is investigated under different experimental conditions (varied adsorbent dose, temperature, pH, and contact time) for reactive dyes. The maximum removal efficiency of 91% is obtained at the optimized experimental condition. Thus the study emphasizes that the no-cost Nigella Sativa seed-waste can be used as an effective bio-adsorbent for reactive dye removal from dye effluents.