The rising demand for high-end equipment manufacturing across the energy, electronics, and aerospace industries has necessitated the development of effective methods for joining dissimilar materials, particularly metals. Dissimilar metal brazing is a notable joining technique owing to its advantages such as low joining temperatures, efficient sealing capability, and applicability to complex structures; it is therefore a central topic in materials processing research. However, dissimilar metal brazing faces significant technical challenges that impede its broader industrial use. Differences in the physical and chemical properties of the base materials, such as melting points, thermal expansion behaviors, and chemical reactivities, can cause problems such as poor wetting of filler metals, generation of residual stresses (leading to joint cracking), and the formation of brittle intermetallic compounds that degrade mechanical strength. Additionally, base materials with irregular shapes further complicate the brazing process, leading to uneven heat distribution, misalignment, and difficulties in achieving effective filler-metal wetting. In this review, the key challenges and underlying mechanisms in dissimilar metal brazing are examined. Current strategies for improving brazability, including surface modification techniques, innovations in high-performance filler metals, and optimization of process parameters, are also systematically reviewed. This review also addresses issues arising from component shape and size differences and proposes viable solutions. Finally, future directions for dissimilar metal brazing are explored, highlighting the potential of intelligent process control systems and the development of environmentally sustainable brazing materials.