Updated project metadata. The synchronization of the internal circadian clock with the external 24-h diurnal cycle is critical for ensuring optimal plant growth fitness. Despite lacking a DNA binding domain, LIGHT-REGULATED WD proteins (LWDs) are essential for sustaining and fine-tuning circadian rhythm1,2. However, the action mechanisms of how LWDs orchestrate the clock gene expressions remain largely elusive. We systematically identified 219 potential LWD1 protein partners at three Zeitgeber times (ZTs) using TurboID-mediated proximity labeling approach. A few LWD1-interacting epigenetic regulators are verified as new regulators of the Arabidopsis circadian clock, flowering time, and light-inhibited hypocotyl elongation. Our data also supports a new working model for LWD1-PSEUDO RESPONSE REGULATORS (PRRs)-TOPLESS (TPL) complex to repress the morning gene CIRCADIAN CLOCK ASSOCIATED (CCA1) in the late afternoon under diel cycles, shaping the expression trough of CCA1 in the late afternoon. Our results revealed a new co-repressor role of LWD1 by working with epigenetic regulators and transcription factors to underpin the precise operation of the circadian clock.