Peroxisomes are highly dynamic organelles indispensable for hepatic lipid metabolism, particularly driving the β-oxidation of very-long-chain fatty acids and regulating cellular redox homeostasis. Despite these critical roles, the disruption of peroxisomal quality control, characterized by stalled pexophagy and reduced lipid metabolism, is a key pathogenic feature in MASLD. Here, we report that Adavosertib effectively promotes hepatic peroxisomal turnover by simultaneously inducing pexophagy and upregulating the expression of ACOX1.  Initially, we identified that WEE1 expression is significantly upregulated in the livers of patients with MASLD and MASH, as well as in HFD-fed mice. In the HFD-induced MASLD mouse model, pharmacological inhibition of WEE1 via Adavosertib administration increased the protein levels of ACOX1. Notably, Adavosertib treatment markedly enhanced the activation of ATM signaling. Consistently, in vitro experiments using primary hepatocytes revealed that Adavosertib treatment elevated the expression of ACOX1 and the activation of ATM, accompanied by a significant increase in TFEB activation. Finally, the induction of pexophagy was further validated by the increased co-localization of lysosomal and peroxisomal markers upon Adavosertib treatment. Taken together, our findings demonstrate that Adavosertib-mediated peroxisomal activation and enhanced quality control represent a promising therapeutic strategy for the alleviation of MASH.