In this study, Al2O3/TiAl composites were synthesized via powder metallurgy by incorporating TiO2 nanoparticles and nanofibers as oxygen sources into Ti-45Al-8Nb pre-alloy powders, followed by vacuum hot-pressing sintering to form in-situ Al2O3 particles as reinforcements. The addition of TiO2 nanofibers results in a better grain refinement effect and a more uniform distribution of Al2O3 particles within the composites. High-temperature tensile testing revealed that the composites prepared using TiO2 nanofibers exhibited slightly higher strengths and significantly improved ductility compared to those synthesized with TiO2 nanoparticles. This work not only introduces a novel additive for fabricating high-performance in-situ Al2O3/TiAl composites but also demonstrates a unique application of TiO2 nanofibers.