A series of Ti1-xZrxO2 solid solutions photocatalysts (x = 0.000, 0.045, 0.090, 0.135, and 0.180) was directly obtained by an ultrasonic spray pyrolysis method. Compared with previous methods for solid solutions, our preparation was very fast. The resulting samples were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, high-resolution transmission electron microscopy, nitrogen adsorption, and UV-vis diffuse reflectance spectroscopy. The characterizations revealed core-shell spherical structures of the resulting solid solutions. We evaluated photocatalytic activities of the solid solutions on degradation of rhodamine B in aqueous solution under simulated solar light. It was found that Ti0.91Zr0.09O2 solid solution exhibited the highest photocatalytic activity among all the as-prepared samples. Its activity was much higher than that of P25. The formation mechanism of core-shell spherical structures was proposed. Moreover, we successfully extended this method to prepare microspheres of ceria and ceria-zirconia solid solutions. We think this general method may be easily scaled up for industrial production of microspherical solid solutions photocatalysts and catalysts.