A novel series of Ag, Cu, and Sn ions incorporated defect pyrochlore K2Ta2O6 photocatalysts were successfully synthesized by facile ion exchange method whereas pristine K2Ta2O6 was prepared by conventional hydrothermal method. All the samples were amply characterized by powder X‐ray Diffraction (PXRD), ultraviolet‐visible diffuse reflectance spectroscopy (UV‐Vis DRS), scanning electron microscopy‐energy dispersive X‐ray spectroscopy (SEM‐EDS) and X‐ray photoelectron spectroscopy (XPS) techniques to understand their phase formation, optical properties, morphology, and chemical composition. The absorption edge of ion‐exchanged samples was red‐shifted remarkably, therefore they would respond under visible light. The photocatalytic activity of all samples was assessed by studying the degradation of methylene blue (MB) dye under visible light irradiation. All samples show activity towards MB degradation and Cu−K2Ta2O6 exhibited superior photocatalytic performance (86 %) compared to others. Different scavenger tests were carried out to identify the reactive species, accountable for the decontamination of aqueous dye solution. Moreover, photoluminescence (PL) measurements were carried out to correlate the separation efficacy of photoinduced charge carriers and photocatalytic performance of all samples. This work may provide valuable information for exploring the as‐prepared photocatalysts towards more energy and environmental applications.