Prepregs are in demand for large production by the composites manufacturing industry to improve the mechanical properties of the load-bearing structural parts. The current prepreg manufacturing is confronted with inadequate resin impregnation, high energy costs, and safety concerns. To address those challenges, in this paper, we proposed a novel thermoset prepreg fabrication strategy that utilizes viscosity controlled by thermal gradient as well as gravity to achieve fast and energy-efficient manufacturing of thermoset prepreg. The concept is based on the localized in-plane thermal assist (LITA) technique, which uses a dynamic capillary effect to induce the wicking of thermoset resins in carbon fibers. This work demonstrated that a bench-scale continuous production of thermoset prepreg with carbon fiber tows can be achieved, and results show that the produced prepreg is B-staged, with the degree of curing as 13.9%. Our calculation suggests that the LITA prepreg fabrication method could save 63.56% of energy compared to the traditional prepreg fabrication methods, and increase the production rate by 133.28% compared to the traditional hot-melt prepreg fabrication method. The LITA prepreg method represents an efficient and eco-friendly composite manufacturing technology to outperform the state-of-the-art energy-intensive prepreg fabrication methods.