The food industry has evolved to create products that meet consumer needs. Factors such as population growth, economic development, and accelerated lifestyle have influenced the search for more nutritious and functional foods. Functional foods are defined as those whose chemical composition provides health benefits, helping in the treatment or prevention of diseases. One of the alternatives for the food industry to respond to these demands is the use of agro-industrial wastes, which are generated and quantified in the order of tons worldwide, and if they are not properly processed, can become highly polluting, generators of greenhouse gases, undesirable odors, and pest incidence. Due to their biological nature, these residues have a high enzymatic activity and are a potential source of metabolites with functional activity, whose extraction and incorporation into raw materials or finished products represent a range of possibilities not only in the food industry but also in those related to pharmacology, materials, and agronomy itself. The use of phytochemicals, such as anthocyanins, flavonols, catechins, tannins, and triterpenes, among others, offers benefits including antioxidant, anti-inflammatory, antihypertensive, and hypoglycemic activities. The adoption of new techniques focused on the extraction, purification, characterization, and application of compounds of interest can not only benefit the increase in the production of functional foods but also favor the circular economy and environmental conservation.