Polyphenols are one of the main classes of secondary metabolites derived from plants offering several health benefits resulting in their use as functional ingredients. Their structural diversity makes them very different from one another in terms of their chemical and physical properties, which makes analysis challenging. The main sources of phenolic compounds are fruits, vegetables, nuts, and processed products, to name but a few. However, attention is now turning to alternative sources of phenolic compounds, namely bio-residues and by-products generated by the agri-food industry. To this end, it is essential to design analytical strategies, thereby allowing the extraction and characterization of phenolic compounds recovered from agri-food residues. Therefore, this chapter aims to give a broad view of the developed methods for the extraction and characterization of polyphenols, including the different workflows and steps involving in the analysis of polyphenols from food stuff and bio-residues.