Unconventional shale reservoirs have become a significant source of hydrocarbon production, yet their recovery factors remain low, typically ranging from 5-10% of the original-oil-in-place (OOIP), as these ultra-low permeability formations are dominated by capillary and surface forces. This review examines the potential of surfactant-induced wettability alteration as an enhanced oil recovery (EOR) technique for shale formations, providing a comprehensive overview of the role of surfactants in altering shale wettability to improve spontaneous imbibition and fluid flow in oil-wet or mixed-wet shales. The mechanisms of wettability alteration, such as ion-pair formation, surfactant adsorption, and micellar solubilization, are discussed in detail. Additionally, common experimental techniques, including contact angle measurements, interfacial tension (IFT) reduction, zeta potential analysis, and spontaneous imbibition experiments used to evaluate surfactant performance, are reviewed. The paper also explores various classes of surfactants tested in laboratory studies, along with field trials conducted in major U.S. shale formations, such as the Eagle Ford, Bakken, and Permian Basin. While challenges related to high salinity, temperature, and complex pore structures persist, significant advancements in surfactant formulations and experimental approaches suggest that surfactant-assisted EOR will play a key role in enhancing oil recovery from shale reservoirs in the future.