Double Taxation Avoidance Agreements (DTAAs) are bilateral treaties designed to mitigate double taxation and facilitate cross-border investment by allocating taxing rights between treaty partners. These agreements incorporate key principles such as residence and source taxation, permanent establishment, and methods for eliminating double taxation. This paper comprehensively discusses the legal framework and principles of DTAAs, essential treaty provisions, empirical evidence on their influence on Foreign Direct Investment (FDI), and future reform perspectives—particularly in the digital economy and anti-abuse contexts.