Vascular smooth muscle cells (VSMCs), switching from a differentiated to a proliferative phenotype, contribute to various vascular diseases. However, the role of long noncoding RNA metastasis-associated lung adenocarcinoma transcript 1 MALAT1 in the phenotype switching of VSMCs remains unclear. Here, we report that the knockdown of MALAT1 promotes the transformation of smooth muscle cells from a proliferative phenotype to a differentiated phenotype. MALAT1 knockdown inhibited cellular proliferation and migration, leading to significant cell cycle arrest in the G2 phase. MALAT1 was downregulated in bone morphogenetic protein-7 (BMP-7)-induced cellular differentiation, while MALAT1 was upregulated in platelet-derived growth factor-BB (PDGF-BB)-induced cellular proliferation. PDGF induced the transformation of smooth muscle cells into a proliferative phenotype accompanied by an increase in autophagy. The downregulation of MALAT1 attenuated PDGF-BB-induced proliferation and migration by inhibiting autophagy. MALAT1 could act as a competing endogenous RNA (ceRNA) to regulate autophagy-related 7 (ATG7) gene expression by sponging miR142-3p. The present study reveals a novel mechanism by which MALAT1 promotes the transformation of smooth muscle cells from contraction to synthetic phenotypes.