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[Display omitted] • An Efficient and value-added flowsheet for recycling rare earth polishing powder waste is proposed. • Coordination enhanced led to high leaching ratios in mild acidic conditions. • The coordination stability constant of Ce3+-ascorbic acid was determined. • High-purity mesoporous Ce-La oxide cube was synthesized by a facile chemical precipitation method. Efficient and environmental-friendly recycling of rare earth polishing powder waste (REPPW) is imperative not only to ecological well-being but also to sustainability of critical rare earth resources. However, the low leaching efficiency of rare earth elements in mild acidic conditions and complicated synthesis procedure of high-end products hindered industrial recycling of REPPW. Herein, an ascorbic acid-H 2 SO 4 system with mild conditions, i.e., ascorbic acid concentration = 0.042 mol/dm3, H 2 SO 4 concentration = 1 mol/dm3, liquid to solid ratio = 20 cm3/g and temperature = 353 K, is proposed for leaching REPPW, in which the leaching ratios of Ce and La reached 96.79 % and 93.81 %, respectively. The coordination stability constants of Ce3+-ascorbic acid, i.e., β 1 = 106.88 and β 2 = 1013.03, were determined by pH-potentiometry, which revealed that the enhanced Ce3+ dissolution in this mild leaching system was attributed to Ce3+-ascorbic acid coordination. Subsequently, a high-purity, mesoporous Ce-La oxide cube was synthesized from the leaching solution by a facile chemical precipitation method at atmospheric pressure and temperature. The product had a composition of 78.07 wt% CeO 2 and 21.93 wt% La 2 O 3 , and its average pore diameter was 7.30 nm. Its reducibility was 1.52 times higher than the theoretical value, suggesting a high potential for catalyzing redox reactions. This work proposes an efficient and value-added process for recycling REPPW, which helps to enlighten the sustainable utilization of secondary rare earth resources. [ABSTRACT FROM AUTHOR]