Residual yeasts from brewing or the production of ethanol represent a low-cost material and a source of proteins and β-glucans that can be enriched with bioactive compounds from vegetable extracts for food application. Biosorption is probably the most prominent phenomenon responsible for the incorporation of chemical compounds into yeasts. Thus, this protocol aimed to guide the reader along the key steps to the biosorption process using residual yeast biomass as sorbent and extracts as sorbate; it will help to follow specific steps, select important operational conditions, give an overview of the most critical factors (e.g., agitation speed, pH, and exposure to light and how to determine the correct equilibrium time), and provide tips on how to avoid some problems during the process (e.g., preventing the incorrect accounting of biosorbed compounds).