The advent of two-dimensional (2D) materials and their capacity to form van der Waals (vdW) heterostructures has revolutionized numerous scientific fields, including electronics, optoelectronics, and energy storage. This paper presents a comprehensive investigation of bandgap engineering and band structure prediction in 2D vdW heterostructures utilizing density functional theory (DFT). By combining various 2D materials, such as graphene, hexagonal boron nitride (h-BN), transition metal dichalcogenides, and blue phosphorus, these heterostructures exhibit tailored properties that surpass those of individual components. Bandgap engineering represents an effective approach to addressing the limitations inherent in material properties, thereby providing enhanced functionalities for a range of applications, including transistors, photodetectors, and solar cells. Furthermore, this study discusses the current limitations and challenges associated with bandgap engineering in 2D heterostructures and highlights future prospects aimed at unlocking their full potential for advanced technological applications.