This study reports facile fabrication of black TiO_2−x/CuFe₂O₄ (Ti³⁺ self-doped titania coupled with copper ferrite), an efficient sonocatalyst for ibuprofen (IBP) mitigation. Compared with TiO_2−x or CuFe₂O₄, the TiO_2−x/CuFe₂O₄ heterojunction displayed enhanced sono-oxidation performance, and their immobilization onto diatomaceous earth (DE) further increased the oxidation rate. The effects of various parameters on sono-oxidation efficiency were studied, such as pH, IBP concentration, catalyst dosage, co-existing microplastics and chemicals, ultrasonic power and frequency, and introduction of persulfate. Quenching tests demonstrated the roles of reactive species. The intermediates during IBP sono-oxidation were determined by the HPLC-MS method, and the acute toxicity was studied. Furthermore, the reaction mechanism was proposed. The sonocatalyst revealed excellent reusability, suggesting that it is promising for wastewater treatment.