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• Novel TiO 2 QDs/BiOBr/BiOCl nanocomposites as efficient photocatalysts are reported. • The TiO 2 QDs/BiOBr/BiOCl (30%) nanocomposite exhibited the highest activity. • Activity was 176-folds greater than TiO 2 in RhB degradation under visible light. • The nanocomposite displayed substantial activity in removal of different pollutants. BiOBr and BiOCl were decorated on TiO 2 QDs through n-p-p heterojunctions by a simple strategy and they were applied for degradation of three organic dyes upon visible illumination. The obtained photocatalysts were analyzed via XRD, FESEM, EDX, UV–vis DRS, PL, BET, TEM, HRTEM, FT-IR, EIS, XPS, and transient photocurrent measurements. The TiO 2 QDs/BiOBr/BiOCl nanocomposite with 20% wt. of BiOBr and 30% wt. of BiOCl displayed superior photoability in the degradation of methylene blue, rhodamine B, and fuchsine, which was almost 34.5, 176, and 78.7-times larger than TiO 2 and 27.8, 13.5, and 51.5-folds greater than TiO 2 QDs, respectively. The results show that the construction of intimate n-p-p heterojunctions between BiOBr, TiO 2 QDs, and BiOCl counterparts leads to enhanced visible-light harvesting and improved charge separation, resulted efficiently increased photocatalytic activity. The trapping results proved that h+, •O 2 −, and OH• species have considerable effects on the degradation reaction. We think that the improved efficiency of the ternary TiO 2 QDS/BiOBr/BiOCl photocatalyst is a splendid alternative for the removal of toxic contaminants from wastewater. [ABSTRACT FROM AUTHOR]