The push for decarbonization necessitates the development of clean and efficient energy conversion technologies. Among these, the chemical looping platform has emerged as a promising approach, albeit with challenges such as high operating temperatures. This necessitates the design of high-performance chemical looping carriers. In this study, we explore the potential of nanosized oxygen carriers, noted for their high reactivity, for the chemical looping combustion of methane (CH4). LaFeO3, a widely investigated perovskite-type mixed metal oxide known for its effectiveness as an oxygen carrier, is examined. Nanosized LaFeO3 is synthesized by embedding LaFeO3 onto mesoporous silica matrix (LFO-SBA15), and its reactivity is benchmarked against bulk-scale LaFeO3 supported on SiO2 (LFO-SiO2). The nanosized carrier demonstrates a ∼ 1000% improvement in reactivity compared to the bulk carrier. This enhancement is attributed to the formation of a highly reactive cubic phase of LaFeO3 at the nanoscale, in contrast to the orthorhombic phase present in bulk-scale LaFeO3. This finding is supported by density functional theory calculations, which reveal that the cubic phase of LaFeO3 facilitates the formation of oxygen vacancies and lowers the energy barrier for CH4 dissociation. This work highlights the potential of nanosized LaFeO3 for the chemical looping combustion of CH4, providing valuable guidance for the rational design and development of high-performance chemical looping carriers.