Proanthocyanidins, also known as condensed tannins, are oligomeric flavonoids found in various plants such as seeds, fruits, and leaves, and they offer health benefits. In vitro, in vivo, and clinical trials can demonstrate and confirm the appropriate dosage for their development in the health sector. The aim of this review article is to provide a systematic overview of the health benefits of proanthocyanidin compounds. The review process was conducted online using websites such as Google Scholar, NCBI, ScienceDirect, NIH, and PubMed with the keywords “in vitro, in vivo, and clinical trials of proanthocyanidin compounds”. The review results indicate that in vitro, in vivo, and clinical studies on proanthocyanidin compounds show health benefits such as antidiabetic, antioxidant, antibacterial, immunostimulant, insomnia therapy, analgesic effects, anthelmintic agents, and potential for COVID-19 prevention and treatment.