Excessive vascular smooth muscle cell (VSMC) proliferation and migration are the main contributors to the symptoms of lower-extremity arteriosclerosis obliterans (ASO). Previous studies suggested that microRNAs (miRNAs) regulate VSMC activity. Nevertheless, the molecular mechanisms by which they do so are unclear. The present study aimed to identify the biological processes accounting for the effects of miR-140-3p on VSMCs in ASO. The expression levels of miR-140-3p in clinical samples were analyzed by real-time polymerase chain reaction. An ASO cell model was established to investigate the expression of miR-140-3p on VSMCs. The transwell® assays and MTT assays were used to assess migration and proliferation. The interaction between RhoA and miR-140-3p was verified using the Dualluciferase reporter assay. Western blot technique was used to identify RhoA, RhoA-associated protein kinase 1 (ROCK1), and ROCK2. We discovered that miR-140-3p inhibited the proliferation, migration, and invasion but promoted the apoptosis of VSMCs, and RhoA was its downstream target gene. RhoA, ROCK1, and ROCK2 were upregulated in vascular tissues damaged by ASO compared to normal, healthy arteries. MiR-140-3p also decreased RhoA, ROCK1, and ROCK2 mRNA and protein expression. Overall, the present work partially elucidated the mechanism by which miR-140-3p regulates VSMC function and offered novel insights into potential therapeutic approaches for patients with lower-extremity arteriosclerosis obliterans.