Allium sativum L. (garlic) and Allium cepa L. (onion) have been significant herbs since ancient times, extensively utilized by various communities globally. Both plants offer a wide array of benefits and applications in medicine, cosmetics, and agriculture. They have proven to be effective in treating or preventing various conditions, including cancer, coronary heart disease, hypercholesterolemia, type 2 diabetes, obesity, and hypertension. Garlic and onion exhibit a range of medicinal properties. For instance, compounds such as allyl sulfide derivatives are known to be the main active components responsible for garlic's anticancer effects by inhibiting tumor cell growth and demonstrating chemopreventive properties. Regarding agricultural applications, A. sativum and A. cepa are known for their insecticidal, antifungal, and nematicidal properties, making them valuable as natural pesticides. Furthermore, garlic and onion are recognized for their anti-aging and anti-inflammatory characteristics, crucial in skincare treatments. This review aims to provide insights into the therapeutic, cosmetic, and agricultural uses of Allium sativum L. (garlic) and Allium cepa L. (onion), contributing to the advancement of knowledge to further optimize the beneficial utilization of both species through experiments, clinical studies, and industrial applications.