<p>Harnessing solar energy through photocatalysis offers a promising pathway for sustainable energy conversion and environmental remediation. Central to this progress is the development of efficient photocatalysts capable of activating inert N₂ molecules under mild conditions. Recently, dual-atom catalysts (DACs) have emerged as a transformative class of materials that bridge the gap between single-atom and nanoparticle catalysts by providing synergistic bimetallic active sites with maximized atomic utilization. This review concisely summarizes recent advances in the coordination microenvironment, structural design, and catalytic mechanisms of transition metal-based dual-atom catalysts (TM-DACs) for photocatalytic N₂ conversion. Particular emphasis is placed on how electronic coupling, metal–metal interactions, and coordination configuration of TM-DACs govern charge transfer dynamics, adsorption behavior, and reaction kinetics during the N₂ reduction process. Synthesis strategies, characterization techniques, and mechanistic pathways of TM-DACs are comprehensively discussed, highlighting their advantages over single-atom systems. Furthermore, emerging trends and challenges in developing noble metal-free, earth-abundant DACs for efficient NH₃ production are outlined. This review aims to provide fundamental insights and design principles for constructing next-generation TM-DACs for highly efficient and sustainable photocatalytic applications.</p> Graphical Abstract <p>Schematic of the coordination microenvironment and dual-metal synergy in transition metal-based dual-atom catalysts (TM-DACs) for photocatalytic N₂ fixation. Design strategies, active site interactions, charge transfer pathways, and reaction mechanisms are highlighted to guide the development of effective and sustainable photocatalysts for NH₃ production.</p> <p></p>