<p>Stimuli-responsive soft actuators are capable of converting external stimuli into macroscopic mechanical motion and have shown extensive applications in soft robots, flexible wearable electronics, and artificial muscles. Owing to their abundant surface-active sites, excellent dispersibility, high structural anisotropy, and diverse physicochemical responsiveness, colloids have served as ideal functional fillers or responsive units for the construction of stimuli-responsive soft actuators. This enables the design of soft actuators with multi-field coupled responses and complex motion patterns, overcoming the limitations of traditional homogeneous materials. This review focuses on the most recent research advances in stimuli-responsive soft actuators based on colloidal nanomaterials. Following a detailed introduction of colloids currently applied in actuation systems, five types of colloid-based soft actuators, including light-responsive, heat-responsive, magnetically responsive, electrically responsive, and solvent-responsive actuators, are systematically summarized, with a focus on their actuation mechanisms, fabrication methods, and corresponding actuation behaviors. Finally, several typical applications of these actuators, such as soft grippers, artificial muscles, and biomimetic robots, are highlighted to provide an intuitive perspective on their application areas. This review is expected to offer novel inspirations for the construction of next-generation high-performance and intelligent actuators.</p>