With the increasing incidence of retinopathy of prematurity (ROP) and the gradual emergence of side effects associated with existing treatments, the development of novel nano-therapy strategies for ROP has become critically urgent. The aim of the current study was to explore the possibility of developing PLGA nanoparticles loaded with rapamycin (RPM) (RPM-PLGA NPs) for the sustained release of RPM as a nano-therapy for ROP intervention. RPM-PLGA NPs were prepared using a nanoprecipitation method, and their physicochemical properties were characterized. The safety profile and therapeutic efficacy of RPM-PLGA NPs were evaluated in BV2, HUVEC cells and in an oxygen-induced retinopathy (OIR) mouse model. RPM-PLGA NPs of 144.23 ± 3.40 nm, a polydispersity index of 0.05 ± 0.02, an encapsulation efficiency of 81.39%, and a drug loading capacity of 16.28% were successfully prepared. The sustained and gradual release of RPM from these NPs was achieved for over 35 days. It was demonstrated that RPM-PLGA NPs had no significant effect on the viability and migration of BV2 and HUVECs. In the oxygen-induced OIR model, RPM-PLGA NPs significantly reduced the areas of vaso-obliteration and pathological neovascularization in the mouse retina, showing superior therapeutic effects compared to RPM alone. These findings validated the feasibility of RPM-PLGA NPs as an intravitreal injection for the treatment of ROP. It is believed that the current study could provide promising experimental data for nano-therapy as an effective and superior treatment for ROP with few side effects.