Anti-apelin antibodies and antigen-binding fragments thereof are described. Also described are nucleic acids encoding the antibodies, compositions comprising the antibodies, and methods of producing the antibodies and using the antibodies for treating or preventing diseases such as diabetic retinopathy (DR), including proliferative diabetic retinopathy (PDR) and non-proliferative diabetic retinopathy (NPDR), age-related macular degeneration (AMD), diabetic macular edema (DME), macular edema following retinal vein occlusion (RVO), retinal degeneration, myopic choroidal neovascularization (mCNV), diabetic nephropathy, chronic kidney disease (CKD), non-alcoholic steatohepatitis (NASH), liver cirrhosis, plaque neovascularization, rubeosis iridis, neovascular glaucoma, corneal neovascularization (CNV), retinopathy of prematurity (ROP), retinopathy, macular degeneration, ovarian hyperstimulation syndrome (OHSS), uterine bleeding, endometriosis, endometrial hyperplasia and cancer, myometrial leiomyomas, adenomyosis, cancer (e.g., solid tumors and hematologic malignancies), fibrosis, and/or associated complications.