Atherosclerotic plaque rupture is an important pathophysiologic mechanism of acute coronary syndrome. Emerging microRNAs (miRNAs) have been implicated in the atherosclerotic plaque formation and macrophage autophagy during the development of atherosclerosis (AS). Hence, this study was conducted to explore the role microRNA-135b (miR-135b) in macrophages and atherosclerotic plaque in mouse models of AS. The expression of miR-135b and erythropoietin receptor (EPOR) was altered in atherosclerotic mice to clarify their effect on inflammation, cell activities of aortic tissues, and macrophage autophagy. The obtained findings unraveled that miR-135b was upregulated and EPOR was downregulated in atherosclerotic mice. Upregulated miR-135b expression promoted cell apoptosis and inflammation, along with inhibited cell proliferation and decreased macrophage autophagy. Notably, miR-135 was validated to target EPOR and activate the PI3K/Akt signaling pathway. Moreover, miR-135b inhibition attenuated inflammation, atherosclerotic plaque development, and promoted macrophage autophagy. Besides, the effect of miR-135b inhibition was reversed in response to EPOR silencing. Taken conjointly, the study revealed that inhibition of miR-135b promoted macrophage autophagy and atherosclerotic plaque stabilization in atherosclerotic mice by inactivating the PI3K/Akt signaling pathway and upregulating EPOR.