Highly ordered macro-mesoporous anatase titanium dioxide (TiO₂) flakes were synthesized by a sol–gel method in an acidic medium, using fresh natural rose (Rosa hybrida L.) petals and triblock copolymer P123 (EO₂₀PO₇₀EO₂₀) as dual templates. The resulting flakes were characterized by Raman spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and nitrogen adsorption–desorption analysis. The results reveal that the bimodal porous material is in the anatase phase, and the three-dimensionally ordered macroporous walls are composed of highly ordered mesopores. The Brunauer–Emmett–Teller (BET) surface area and the average size of mesopores are 125.91 m² g⁻¹ and 4.79 nm, respectively. The photocatalytic activity of the porous TiO₂ flakes was evaluated by photodegrading rhodamine B (RhB) under ultraviolet (UV) light. The obtained TiO₂ flakes exhibited a slightly higher photocatalytic activity than commercial photocatalyst Degussa P25.