<p>This study investigates the role of Fe dopant induced defects in tailoring the physicochemical and functional properties of hydrothermally synthesized BaSnO₃ (BSO) nanostructures. XRD and Raman analyses confirmed the successful incorporation of Fe into the cubic perovskite lattice without the formation of secondary phases. The FTIR spectra further revealed distinct vibrational bands corresponding to Ba–O and Sn–O stretching modes, substantiating the chemical bonding and integrity of the perovskite framework. Morphological analysis showed irregular rod-like nanostructures, indicative of dopant-driven growth modifications. Optical studies revealed Fe-induced modulation of the electronic band structure, resulting in measurable band gap reduction and enhanced defect-related visible emissions in the photoluminescence spectra. Magnetic characterization demonstrated robust room-temperature ferromagnetism in all Fe-doped samples, with M–H loop analysis and ESR measurements confirming oxygen-vacancy–mediated exchange interactions as the origin of magnetization. These findings establish Fe-doped BSO as a multifunctional material that simultaneously exhibits tunable optical band gaps, defect-driven luminescence, and stable ferromagnetism, underscoring its potential for application in dilute magnetic semiconductor–based spintronic and optoelectronic devices.</p>