Mammalian autophagy-related protein Atg8, including the LC3 subfamily and GABARAP subfamily. Atg8 proteins play a vital role in autophagy initiation, autophagosome formation and transport, and autophagy-lysosome fusion. GABARAP subfamily proteins (GABARAPs) share a high degree of homology with LC3 family proteins, and their unique roles are often overlooked. GABARAPs are as indispensable as LC3 in autophagy. Deletion of GABARAPs fails autophagy flux induction and autophagy lysosomal fusion, which leads to the failure of autophagy. GABARAPs are also involved in the transport of selective autophagy receptors. They are engaged in various particular autophagy processes, including mitochondrial autophagy, endoplasmic reticulum autophagy, Golgi autophagy, centrosome autophagy, and dorphagy. Furthermore, GABARAPs are closely related to the transport and delivery of the inhibitory neurotransmitter γ-GABA_A and the angiotensin II AT1 receptor (AT1R), tumor growth, metastasis, and prognosis. GABARAPs also have been confirmed to be involved in various diseases, such as cancer, cardiovascular disease, and neurodegenerative diseases. In order to better understand the role and therapeutic potential of GABARAPs, this article comprehensively reviews the autophagic and non-autophagic functions of GABARAPs, as well as the research progress of the role and mechanism of GABARAPs in cancer, cardiovascular diseases and neurodegenerative diseases. It emphasizes the significance of GABARAPs in the clinical prevention and treatment of diseases, and may provide new therapeutic ideas and targets for human diseases. GABARAP and GABARAPL1 in the serum of cancer patients are positively correlated with the prognosis of patients, which can be used as a clinical biomarker, predictor and potential therapeutic target.