This chapter unveils the hidden potential of cauliflower by-products and explores their economic importance, biochemical composition, and diverse biocompounds. Cauliflower, a healthy food source, also possesses several health-promoting characteristics. The by-product of cauliflower mainly consists of leaves, stalk, and florets and constitutes a remarkable portion of waste in the agriculture fields. These unexplored by-products of cauliflower are rich sources of bioactive phytocompounds (secondary metabolites) such as glucosinates, phenolic compounds, and flavonoid contents. Additionally, these secondary metabolites in by-products have significant antimicrobial, anticancer, antioxidant, and anti-inflammatory properties, making them a vital addition in nutraceuticals, pharmaceuticals, and food industries. Furthermore, this chapter also focuses on the nutritional profile of the reported by-products of cauliflower, which is mainly composed of protein, dietary fiber, vitamins, cellulose, hemicellulose, and mineral elements. This chapter has also discussed cauliflower by-products in bioenergy production (biogas, biomass, bioethanol, and biochar production) along with their human health-promoting and nutritional applications. The valorization of by-products for non-edible purposes reduces agricultural waste and produces sustainable energy, aids in developing a circular economy, and reduces the cost of non-renewable energy sources. Conclusively, this chapter provides an inclusive exploration of bioactive compounds derived from by-products of cauliflower, transcending their edible and non-edible potential to understand agro-economic and environmental prospects. This concise overview offers valuable insights for researchers, policy makers, and health experts to understand cauliflower by-products’ health and non-health potential.