Rigid robots have taken on a variety of automated manufacturing tasks and have made a huge contribution to industrial development; however, they are not suitable for further wearable applications due to their rigid and bulky structure, poor environmental adaptability, and low safety. Soft robots, which are mainly fabricated with flexible or elastomeric materials, can easily adjust to environmental changes and accomplish complex tasks, offering a new paradigm to achieve human–machine compliance. Soft robots do not replace rigid robots but add diverse features for softer robotic applications. In particular, the use of flexible actuators in robotic systems can realize certain intelligent functions, enrich soft robotic systems and migrate academic research to engineering applications. Currently, the application of flexible actuators in soft robotic fields is still at the embryonic stage. However, tremendous application spaces can be envisaged when combining flexible actuators with soft wearable robotics. Therefore, the current flexible actuators that rely on different external stimuli are addressed herein, and their materials, designs, and approaches suitable for soft robotic applications are highlighted. The application advancement and future perspective of flexible actuator prototypes toward various soft robotics are also discussed.