The increasing demands for high-speed imaging, aerospace, and optical communication have driven in-depth research on broadband photodetectors with high sensitivity and fast response. Two-dimensional (2D) materials have atomic-scale thickness, tunable bandgaps, and excellent carrier transport properties, making them ideal candidates for next-generation optoelectronics. However, their limited light absorption and intrinsic recombination losses remain key challenges. This paper provides an overview of recent progress of 2D-material-based broadband photodetectors. First, the fundamental optoelectronic properties of 2D materials, including bandgap modulation, carrier dynamics, and light–matter interactions, are discussed to clarify their broadband detection potential. Representative material systems, such as narrow-band gap semiconductors, 2D topological materials, and perovskites, are summarized, showing the detection ability from the ultraviolet to the mid-infrared regions. To overcome intrinsic limitations, four optimization strategies are highlighted: heterostructure engineering for efficient charge separation and extended spectral response; defect engineering to introduce mid-gap states and enhance sub-bandgap absorption; optical field enhancement through plasmonic nanostructures and optical cavities to improve responsivity; strain engineering for reversible band structure tuning, particularly suited for flexible devices. These strategies have achieved significant improvements in responsivity, detectivity, and bandwidth, with some devices implementing ultrabroadband detection and multifunctionality. In summary, 2D materials and their hybrids have shown great potential in broadband photodetection, with progress made in material innovation and device architecture optimization. The reviewed strategies, including heterostructure integration, defect modulation, optical field enhancement, and strain engineering, collectively demonstrate the different ways of overcoming intrinsic limitations and improving device performance. Looking ahead to the future, the reasonable combination of these methods is expected to further expand the detection window, improve sensitivity, and achieve multifunctional operations, thereby paving the way for the multifunctional applications of the next-generation broadband photodetectors in imaging, sensing, and optoelectronic systems.