Ti–Mn based alloys are identified as a highly potential mediator for large-scale hydrogen storage due to their attractive features of low cost, high hydrogen storage capacity, and benign reactive conditions during hydrogen (de)absorption. However, the low activation efficiency, poor cyclic stability, and notable hysteresis during (de)hydrogenation are still challenging. Herein, to further improve the overall hydrogen storage performance, we focus on the effect of annealing treatment on the microstructure and hydrogen storage characteristics based on a TiV0.45Mn1.5 alloy. Studies show the alloy annealed at 850 °C can absorb 2.09 wt% H2 at 5 MPa and present lower hysteresis. On the other hand, annealing at a higher temperature boosts the activation process and prolongs the cycling stability, of which the alloy annealed at 950 °C is able to absorb hydrogen without activation at room temperature due to the reduced oxidation content, and exhibits nearly zero attenuation after (de)hydrogenation 100 cycles, whereas the segregated TiV0.45Mn1.5 alloy losses 4.43 % capacity. This study provides an approach for further improving the hydrogen storage properties of Ti–Mn based hydrogen storage alloys and offers the possibility of further applications for solid-state hydrogen storage technology.