This study investigated the impact of aging heat treatment time on the mechanical properties of NiTi triply periodic minimal surface structures fabricated through laser powder bed fusion. X-ray diffraction analysis results indicate that with increasing aging time, the NiTi2 phase precipitates while the content of the B19’ phase decreases. At 10 h of aging time, the Ni4Ti3 phase becomes evident in the sample. The differential scanning calorimeter results show that R phase transformation occurs, and the phase transformation temperature increases when the aging time reaches 6 h. Microhardness increases with aging time, peaking at 477.8 HV after 10 h. Compression experiment results reveal a maximum elastic modulus of 1262.82 MPa for the gyroid sheet-shaped structure achieved after 2 h. In addition, the superelasticity test indicates the highest recoverable strains at 2%, 4%, and 6% compressive strain for the gyroid rod-shaped structure after aging for 10 h. In cyclic compression experiments, the ratio of shape memory recovery increases from 40% at 0 h to 97% at 6 h. Fracture analysis results show that the transition in the fracture mechanism from brittle fracture to quasi-cleavage fracture occurs after aging heat treatment.