The expanding global population and rising demand for food production have contributed to the increase in the generation of by-products. By-products can be of animal and vegetable origin, but in this chapter, vegetable by-products will be addressed due to the compounds of interest. Around 1.3 million tons of by-products are produced annually, consisting of bark, seeds, and bagasse, which can be obtained at all stages of the production chain, marketing, and consumption. However, most of these by-products are destined for disposal in landfills and incineration, which leads to several environmental problems. Many agro-industrial by-products are considered valuable raw materials for several industries, becoming a central strategy in developing new products and processes. Therefore, it is necessary to properly manage these by-products using recovery strategies. By-products can be used to extract compounds of interest, known as bioactive compoundsBioactive compounds, that can be defined as essential and nonessential biologically active constituents, such as phenolic compounds, alkaloids, and terpenes, which are present in nature, can be part of the diet, and have beneficial effects on health due to their biological properties, arousing interest in their extraction. These bioactive compoundsBioactive compounds are generally extracted by conventional extraction methods; however, more sustainable and environmentally friendly methods are being studied as alternatives to conventional methods, due to the negative impacts on health, the environment, and the economy. In this context, the application of emerging extraction technologies in the food industry has been widely studied and investigated. Methods such as microwave-assisted extraction (MW), ultrasound (US), and eutectic solventsEutectic solvents (ES) (ES) have demonstrated several advantages over conventional extraction methods, such as shorter extraction time, more moderate temperatures, and reduced use of solvents. Therefore, this chapter aims to show an overview of the use of emerging technologies in the extraction of terpenes, alkaloids, and phenolic compounds present in agro-industrial by-products, offering more sustainable approaches in the valorization of these by-products and in obtaining high-added value products.