Pharmacological activation of peroxisome proliferator activated receptor alpha (PPARα) is an effective treatment for dyslipidaemia. Autophagy dysfunction has been observed in disorders of lipid metabolism, especially in the liver. In this study, we have identified the PPARα as a potential inhibitor of the autophagy pathway, reducing the correlate of forkhead box protein O1 (FoxO1) and enhancing endoplasmic reticulum (ER) stress. This study was performed in chow (CH) diet fed mice treated with the PPARα agonist, fenofibrate (FB, 100mg/kg/day). PPARα-induced CH displayed a significant suppression of autophagy action (p<0.01 for all), which is indicated by a reduction in key autophagy proteins Atg5, Atg7 and p62 (p<0.05; FB vs. untreated). Moreover, the inhibited autophagy pathway abolished FoxO1 (p<0.01 FB vs. untreated). Interestingly, this suppressed autophagy is associated with enhanced activation of unfolded protein response (UPR) signalling, namely IRE/XBP1 and PERK/eIF2α, indicating ER stress stimulation. We further examined whether the PPARα is required for FB to alter the pathway of autophagy in the PPARα knockout (KO) model. Results showed that PPARα is required for FB to suppress the autophagy pathway (p<0.05, p<0.01; FB vs. untreated), and correspondingly to induce enhanced ER stress of the UPR pathway (p<0.01; FB vs. untreated). Our data indicate a possible role of the autophagy pathway in mediating the metabolic effects induced by PPARα activation.