This chapter explores the application of pressurized fluid-assisted extraction (PFAE) technology for the extraction of essential oils from food by-products. PFAE, a modern and efficient extraction method, uses pressurized fluids as solvents to enhance the extraction of bioactive compounds from various food residues. The chapter provides an in-depth overview of the principles and mechanisms of PFAE, comparing it with traditional extraction techniques such as steam distillation and solvent extraction. Historical advancements and current innovations in PFAE are also discussed, along with case studies demonstrating its success in the food industry. Detailed sections outline the required equipment, reagents, and solvents for the extraction process, followed by step-by-step instructions for sample preparation, extraction, and postextraction processing. Emphasis is placed on the optimization of extraction parameters, including temperature, pressure, and solvent ratios to achieve maximum yield and efficiency. The chapter concludes with safety protocols, troubleshooting tips, and best practices for long-term storage of extracts, making it a comprehensive guide for researchers and practitioners interested in utilizing PFAE for essential oil extraction from food by-products.