Introduction: Proprotein convertase subtilisin/kexin type 9 (PCSK9) plays a key role in cholesterol homeostasis. Cilostazol exerts favorable cellular and metabolic effects; however, the effect of cilostazol on the expression of PCSK9 has not been previously reported. Hypothesis: Our study aimed to investigate the potential mechanisms of action of cilostazol on the expression of PCSK9 and lipid homeostasis. Methods: We evaluated the effects of cilostazol on the expression of PCSK9 in HepG2 cells and evaluated potential molecular mechanisms by measuring signaling molecules in the liver and serum lipid profiles in high-fat diet-induced obese mice and normal chow-fed mice. Additionally, the baseline and post-treatment serum PCSK9 levels of obese and non-obese human participants treated with cilostazol were measured. Results: Cilostazol treatment significantly induced the messenger RNA and protein expression of PCSK9 in HepG2 cells and enhanced PCSK9 promoter activity. Chromatin immunoprecipitation assays confirmed that cilostazol treatment enhanced PCSK9 transcription by binding to peroxisome proliferator-activated receptor-γ (PPARγ) via the PPARγ DNA response element. PPARγ knockdown attenuated the stimulatory effect of cilostazol on PCSK9. In vivo experiments revealed that cilostazol treatment increased serum levels of PCSK9 in normal mice but significantly reduced PCSK9 levels in obese mice (Figure). Clinical data showed that cilostazol treatment significantly reduced serum PCSK9 levels in patients with obesity. The expressions of relevant miRNAs also showed consistent results. Conclusions: The obesity-dependent effects of cilostazol on PCSK9 expression observed from bench to bedside demonstrate the therapeutic potential of cilostazol in clinical settings.