Abstract: Under the global trend of energy transition and carbon neutrality, the efficient conversion of carbon dioxide (CO₂) into high-value-added chemicals and fuels has emerged as a critical pathway for mitigating greenhouse gas emissions. Photothermal synergistic catalysis, which combines light and thermal energy, has demonstrated remarkable catalytic performance by overcoming the inherent limitations of standalone thermal catalysis and photocatalysis. The core of this technology lies in the synergistic interplay between light and heat during energy transfer and conversion, wherein electronic excitation plays a pivotal role. In this context, the electronic excitation mechanisms involved in photothermal CO₂ conversion are systematically categorized, and the specific roles of light and heat in various catalytic systems are elucidated. Three major pathways for excited electron generation are highlighted: semiconductor interband transitions, non-radiative decay (Landau damping) in plasmonic metals, and hot carrier generation. The complete lifecycle of high-energy electrons is comprehensively traced—from generation on the femtosecond scale, through relaxation, migration, and interfacial separation on the picosecond to nanosecond scale, to their final injection into CO₂ molecules, thereby initiating chemical bond reorganization. Furthermore, key intrinsic factors (material properties) and extrinsic factors (structural and environmental conditions) that influence electron excitation and utilization efficiency are summarized. Four advanced strategies for enhancing electron utilization efficiency are evaluated: plasmonic engineering, band engineering, interface engineering, and thermal management strategies. Finally, current challenges and future research directions are outlined, with the aim of providing theoretical insights and technical guidance for the rational design of highly efficient photothermal catalytic systems.