In this work, cerium carbonate hydroxide (CeCO3OH) was synthesized by a facile sonochemical reaction. The CeCO3OH particles were blended with thermoplastic polyester elastomer (TPEE) and aluminum phosphinate (AlP) to fabricate the fire-retardant materials. Morphology analysis results indicated that CeCO3OH was uniformly dispersed in TPEE. Thermogravimetric analysis results demonstrated that the additives composed of CeCO3OH and AlP led to the slight reduction of thermal decomposition temperature and maximum mass loss rate of TPEE composites. Compared with neat TPEE, all the TPEE/AlP/CeCO3OH composites achieved the V-0 rating in Underwriters Laboratories (UL) 94 testing. Their limiting oxygen index values were also higher than those of neat TPEE and TPEE/AlP. In cone calorimetry testing, the peak heat release rate of TPEE/12AlP/3CeCO(3)OH decreased from 1190 kW/m(2) for neat TPEE to 530 kW/m(2) with a reduction of 55%. Residue analysis showed that the presence of CeCO3OH in TPEE/AlP promoted the formation of compact protective char layer resulting in the improved fire-resistant performance. The incorporation of CeCO3OH also enhanced the tensile properties of TPEE composites.