This book offers a comprehensive overview of bioactive phytochemicals within by-products from leaf, stem, root, and tuber vegetables, and it explores the valorisation of these vegetable cultivation and processing by-products, not only as a source of valuable bioenergy but also for health purposes. Divided into 16 chapters, the book begins with an introduction to the economic significance of biowaste generated from vegetable cultivation and processing, setting the stage for subsequent chapters that cover the phytochemical, nutritional, biochemical and physicochemical properties of vegetable processing wastes and their multifaceted applications. Readers will find valuable insights into the valorisation of process by-products from diverse vegetables like cabbage, spinach, watercress, asparagus, celery, kohlrabi, beetroot, carrot, celeriac, turnip, sweet potato, potato and taro. In each chapter, readers will find an economic perspective for each biowaste, the chemical analysis of the bioactive compounds, their biological and functional properties, and relevant food and non-food applications of extracts and bioactive compounds from vegetable by-products. This book, coupled with its companion volume, " Bioactive Phytochemicals in By-products from Bulb, Flower and Fruit Vegetables" serves as an indispensable tool for students, scholars, and researchers seeking to expand their knowledge within this field in agricultural and nutritional sciences. It also extends its relevance to professionals within the food industry, offering the latest insights and findings from cutting-edge research.