Industrial wastewater poses a serious threat to human health and the environment. The rising demand for an easy, efficient, environment‐friendly, and cost‐effective method for wastewater treatment has paved the way for the photocatalytic degradation of wastewater. Organic dyes, which comprise a major portion of organic pollutants in industrial wastewater, are highly toxic and carcinogenic. The hydrothermal method, being economical, easily available, and environmentally friendly, is used to prepare the time‐varying KBiFe2O5 samples. KBiFe2O5 is a lead‐free (nonhazardous), low‐bandgap brownmillerite‐structured crystalline material that can use a wide range of solar spectrum. Their phase purity is also confirmed by powder X‐ray diffraction (XRD), UV–Vis diffuse reflectance spectrophotometer (UV–Vis DRS) is done to confirm the bandgap value and Fourier transform infrared (FTIR) spectroscopy is performed to identify the chemical bonds in the material. Degrading textile organic effluent methylene blue (MB) dye under visible light and comparing its photodegradation performance are conducted to investigate the synthesized samples’ photocatalytic properties. The photocatalytic activity is relatively enhanced by adding H2O2 in a precise amount. So, the synthesized samples effectively demonstrate photocatalytic behavior, which has been used for wastewater remediation purposes.