Liquid crystal elastomers (LCEs), owing to their intrinsic anisotropic property and capability of generating programmable complex morphologies under heat, have been widely used for applications ranging from such as soft robotics, artificial muscles, energy harvesters, photonic display, and tissue engineering. To fulfill the applications under various circumstances, high actuation efficiency, high mechanical strength, large heat and electrical conductivity, or responses to multiple stimuli are required. In this thesis, we focus on LCE nanocomposites for light actuation and energy harvesting. We investigate the interactions between the nanofillers and the LCE matrix. By surface modification of the fillers, we improve their dispersity in the LCE matrix without greatly sacrificing the intrinsic actuation strain of the LCEs. we not only design LCE composites from the aspects of enhancing the properties or endowing extra functionalities of the LCEs by embedding nanofillers, but also consider whether the actuation of the LCEs can generate signals or feedback on the nanofillers, thus benefiting the nanofillers at the same time.We first introduce the gold nanorod (AuNRs) into the LCEs. Through proper surface modification by thiol-terminated polyethylene glycol, AuNR/LCE films with up to 0.2 wt% AuNRs are successfully fabricated without aggradation. The incorporation of the AuNRs improves the mechanical property and allows excellent photothermal performance, rendering repeated and fast actuation of the films (actuation within 5 s and recovery in 2 s)when exposed to 800 nm light at an average output power of ~1.0 W cm-2, while maintaining a large actuation strain (56%). Further, we show that the same sheet of AuNR/LCE film can be morphed into different shapes simply by varying the motifs of the photomasks, which can be potentially applied to all photoresponsive materials. Then, we develop a 3D-printable photoresponsive AuNR/LCE composite ink, allowing for photothermal actuation of the 3D printed structures with 27 % actuation strain upon irradiation to NIR light (808 nm) at 1.4 W cm−2. Taking advantage of the customized structures enabled by 3D printing and the ability to control locally exposed light, we demonstrate a light-responsive soft robot that can climb on a ratchet surface with a maximum speed of 0.284 mm s−1 (on a flat surface) and 0.216 mm s-1 (on a 30° titled surface), respectively, corresponding to 0.428 and 0.324 body length per min-1. These two works focus on how to enhance the physical property of the LCEs and endow LCEs with a photothermal response without greatly sacrificing the intrinsic actuation strain of the LCEs. Finally, we design and fabricate a lead zirconate titanate (PZT)/LCE energy harvesting device. Specifically, we consider how the LCE can also benefit the nanofillers by utilizing the stress generated from phase transition of the LCE to produce piezoelectric signal of the PZT nanoparticles (NPs) in addition to their intrinsic pyroelectric signal. As a result, PZT/LCE with 27.1 wt% PZT NPs show obvious pyroelectric effect with an open circuit voltage of 4.5 V and a short circuit current of 0.7 nA at a heating speed of 0.2 K s-1, corresponding to a pyroelectric coefficient p of 1.39 nC cm-2 K-1. p can be further improved by increasing the PZT concentration (2.30 nC cm-2 K-1 when PZT loading is 42.7 wt%). The higher pyroelectric coefficient may result from the piezoelectric effect due to the phase transition of the LCE matrix besides the intrinsic pyroelectric effect from PZT.The PZT/LCE composite can be utilized as the power source to drive electronics such as light-emitting diodes, digital watch, and self-powered sensor, demonstrating the potential applications of the flexible energy harvesters and self-powered multifunctional devices.