A facile and efficient approach for the fabrication of mesoporous spherical aggregates of anatase nanocrystals is reported in this paper. Cetyltrimethylammonium bromide was used as the structure-directing agent, and the interaction between cyclohexane microdroplets and the cetyltrimethylammonium bromide self-assemblies led to the assembly of 4-5-nm-sized anatase nanocrystals into spherical aggregates with mesoporous structures. The as-prepared anatase powders exhibited high photocatalytic activity and could be effectively used as the catalyst for the room-temperature photodegradation of a variety of organic dye pollutants in aqueous media including methyl orange, bromopyrogallol red, and methylene blue.