Introduction Textile industry produces large quantities of highly colored effluents, which are generally toxic and resistant to biodegradation. The present study was carried out to find out the efficiency of using gamma radiation to degrade or decontaminate combined textile effluent and its potential application as irrigation water on spleen amaranth. Results The change of absorption spectra, physicochemical parameters of gamma-irradiated textile effluent revealed that all these properties have improved after irradiation at (10-15) kGy. Analysis of ammonium and total nitrogen concentration of the effluent also showed that both of them are increased after irradiation and can be used for irrigation purposes. Application of irradiated textile effluents on spleen amaranth have increased dry mass (10.77 g), plant height (10.53/week), root length (19.00 cm), number of leaves (6/week) compared to the plants which were nourished with raw textile effluent and only water. Elemental analysis showed trace amount of heavy metal uptake by the plant. Moreover, the plants contain mineral nutrients essential for plant growth. Conclusions The treatment of textile effluents by gamma irradiation (10-15 kGy) is a promising tool as it produces zero waste and has the possibility of alternative use for irrigation water with fertilizing properties.