The molecular pathogenesis of choroidal neovascularization (CNV), an angiogenic process that critically contributes to vision loss in age-related macular degeneration (AMD) is unclear. Here we analyzed the role of transforming growth factor (TGF)-β signaling for CNV formation by generating a series of mutant mouse models with induced conditional deletion of TGF-β signaling in the entire eye, the retinal pigment epithelium (RPE) or the vascular endothelium. Deletion of TGF-β signaling in the eye caused CNV, irrespectively if it was ablated in newborn or three-week-old mice. Areas of CNV showed photoreceptor degeneration, multilayered RPE, basal lamina deposits and accumulations of monocytes/macrophages. The changes progressed leading to marked structural and functional alterations of the retina. While the specific deletion of TGF-β signaling in the RPE caused no obvious changes, specific deletion in vascular endothelial cells caused CNV and a phenotype quite similar to that observed after the deletion in the entire eye. We conclude that impairment of TGF-β signaling in the vascular endothelium of the eye is sufficient to trigger CNV formation. Our findings highlight the importance of TGF-β signaling as key player in the development of ocular neovascularization and indicate a fundamental role of TGF-β signaling in the pathogenesis of AMD.