Reduced TiO₂ (titanium dioxide)/black TiO₂ has garnered tremendous attention among researchers due to its superior photocatalytic performance in many applications. Numerous synthetic routes exist in the literature for producing reduced TiO₂ of different colours. This paper has developed a simple, low-cost method to reduce pristine TiO₂ in 30 min using minimal amounts of sodium borohydride (NaBH₄) without the need for harsh conditions and an inert environment. Variation in reduction temperature and NaBH₄/TiO₂ molar ratio produced coloured samples ranging from light grey to pitch black. Characterization of the samples was done through UV-DRS (ultraviolet diffused reflectance spectroscopy), XRD (X-ray diffraction), ESR (electron spin resonance), XPS (X-ray photoelectron spectroscopy), FESEM (field emission scanning electron microscopy) and TEM (transmission electron microscopy). The particle sizes of all samples were in the range of 20–50 nm. Enhanced visible light absorption, reduced bandgap values and presence of defect species (Ti³⁺ and oxygen vacancies) on the surface of the samples were observed, which changed with varying reduction parameters. The optimal sample was found to be the one reduced at 350 ºC using NaBH₄/TiO₂ molar ratio of 0.2 (R-350–0.2). This sample exhibited better photocatalytic activity than pristine TiO₂ and all reduced samples in the degradation of fuchsin basic (FB) dye solution under both sunlight and UV–visible light. The optimal sample, with intermediate defect concentration, had a reduced bandgap value of 2.87 eV as compared to 3.18 eV for pristine TiO₂. Excess defect concentration due to a higher temperature and higher NaBH₄ dosage decreased the activity.