Due to the forecasted overpopulation of the globe and increasing waste production, several insect species are mass produced for animal feeds, fish bait, or human consumption. The yellow mealworm, Tenebrio molitor L. (Coleoptera: Tenebrionidae), is one of the more-popular insects considered for this use. Our review identified that mealworms which thrive at temperatures between 25–28°C with peak larval growth at 70% relative humidity, exhibit a nutritional profile rich in essential amino acids, vitamins, and minerals while serving as a low-fat source. Their frass containing nitrogen, phosphorus, and potassium proves valuable for plant growth, and also induce tolerance to abiotic stress. Notably, mealworms showcase the remarkable ability to biodegrade petroleum-based plastics like polystyrene and polyethylene. Moreover, they can excrete or catabolize mycotoxins, displaying antifungal properties. They show medicinal potential including cardiovascular disease prevention due to the presence of angiotensin-converting enzyme (ACE), and antioxidative properties. Additionally, biodiesel production from dried mealworm larval biomass underscores their significance in sustainable fuel initiatives.