Abnormal neovascularization is an important cause of blindness in many ocular diseases, for which the etiology and pathogenic mechanisms remain incompletely understood. Recent studies have revealed the diverse roles of noncoding RNAs in various biological processes and facilitated the research and development of the clinical application of numerous RNA drugs, including microRNAs. Here, we report the antiangiogenic activity of microRNA-29a (miR-29a) in three animal models of ocular neovascularization. The miR-29a knockout (KO) mice displayed enhanced vessel pruning, resulting in a decreased vascularized area during retinal development. In contrast, miR-29a deletion in adult mice accelerated angiogenesis in preclinical disease models, including corneal neovascularization, oxygen-induced retinopathy, and choroidal neovascularization, while the administration of agomir-29a ameliorated pathological neovascularization. Furthermore, miR-29a exerted inhibitory effects on endothelial cell proliferation, migration, and tube formation capacities. RNA sequencing analysis of retinas from miR-29a KO mice and RNA interference experiments identified platelet-derived growth factor C and several extracellular matrix genes as downstream targets of miR-29a involved in regulating ocular angiogenesis. Our data suggest that miR-29a may be a promising clinical candidate for the treatment of neovascular diseases.