Digital textile printing represents a transformative advancement in the textile industry, offering remarkable design flexibility, precision, and sustainability. Unlike traditional methods, it employs inkjet technology to apply intricate patterns directly onto fabrics, enabling rapid customization, minimal waste, and reduced environmental impact. The process is fundamentally driven by the underlying chemistry of ink formulation which must meet stringent physicochemical criteria such as viscosity, surface tension, stability, and compatibility with specific firbres and treatments. Textile inks are designed with functional additives including surfactants, dispersants, thickeners, and binders, ensuring optimal print quality, colour vibrancy, and resistance to washing, abrasion, and UV exposure. Moreover, alignment between ink chemistry and substrate pre- and post-treatment is essential to achieve durable and high-performance prints. As the industry shifts toward on-demand production, personalization, and environmentally responsible practices, innovations in sustainable ink systems and greener processing techniques are crucial. This chapter explores the critical role of ink and chemical formulation in digital textile printing and highlights how ongoing advancements in this domain are enabling a more circular, efficient, and responsive textile manufacturing ecosystem.