The full-range, high-sensitivity and integratable detection of circularly polarized light (CPL) is critically important for quantum information processing, advanced imaging systems and optical sensing technologies. However, mainstream CPL detectors rely on chiral absorptive materials, and thus suffer from limited response wavelengths, low responsivity and poor discrimination ratios. Here we present a chiral light detector by utilizing valley materials to observe the spin angular momentum carried by chiral light. Delicately designed centrosymmetric metamaterials that can preserve the sign of optical spin angular momentum and greatly enhance its intensity in the near field are harnessed as a medium to inject polarized electrons into valley materials, which are then detected by the valley Hall effect. This enables high-sensitivity infrared CPL detection at room temperature by valleytronic transistors, and the detection wavelength is extended to the infrared. This approach opens pathways for chiral light detection and provides insights into potential applications of valleytronics in optoelectronic sensing.