This chapter provides a comprehensive review on Ashbya gossypii physiology and metabolism, with a particular emphasis on the characteristic traits of this filamentous fungus and its natural metabolic capabilities. It is divided into three subsections. The first subsection covers growth and reproduction, describing the mechanisms of spore germination, hyphal growth, septation and sporulation to perform a full coverage of the fungus lifecycle. The second subsection dives into the natural metabolism of Ashbya gossypii, covering central carbon and nitrogen metabolism with a particular focus on its genetic and metabolic distinctive traits. The third subsection explores in greater detail the natural metabolic capabilities of A. gossypii zooming in on different metabolites of biotechnological interest, by performing a detailed review of the main natural metabolites and the biosynthetic pathways involved in their production. With this critical review, this chapter sets the knowledge base that serves as foundation for understanding the potential of this organism for biotechnological development.