<p>Fear memory is crucial for animals to effectively respond to dynamic environments and survive dangerous stimuli. However, aberrant fear memory contributes to various psychiatric disorders, such as post-traumatic stress disorder (PTSD). Despite its importance, the precise molecular mechanisms underlying fear memory remain insufficiently understood. In this study, we highlight the pivotal role of the epigenetic factor chromodomain Y-like protein (CDYL) in the regulation of fear memory. We discovered that ablation of CDYL in CaMKIIα⁺ excitatory neurons in the forebrain or hippocampus leads to increased fear memory in mice. CDYL is phosphorylated by cyclin-dependent kinase 5 (CDK5) at Ser147, which facilitates tripartite motif containing 32 (TRIM32)-mediated ubiquitination and degradation of CDYL in response to neural activity. Additionally, we developed an interfering peptide that specifically targets the phosphorylation of CDYL at Ser147, resulting in a decrease in contextual fear memory in mice. Collectively, our findings underscore the essential role of CDYL in fear memory and illustrate the modulatory function of CDK5 and TRIM32 on CDYL, positioning CDYL as a promising target for the modulation of fear memory.</p>