This chapter describes the biosynthesis of several important secondary metabolites. These biochemical processes produce a variety of chemical compounds, including colorants, flavorings, and bioactive substances, which play a role in human nutrition and health. Although some of these compounds can also be toxic, most are important supplements. Primary and secondary metabolism are closely linked, with overlaps such as steroids and vitamins, which make a clear separation of metabolic pathways difficult. These interactions shape biochemical diversity and are fundamental to understanding biological processes across organisms. This chapter also explains the biosynthesis of polymeric sugars and provides examples of their technical integrations. Further, the biosynthesis of relevant amino acids as precursors to alkaloids, phenols, as well as polymeric sugars such as cellulose, starch, dextrin, chitin, cyclodextrins, hyaluronic acid, and xanthan is discussed. In addition to the biosynthesis, biotechnological processes with genetically modified platform organisms in industry, applications in medicine, engineering, and the food industry, are discussed with detailed examples.