Hyperactivation of fatty acid biosynthesis holds promise as a targeted therapeutic strategy in prostate cancer (PCa). However, inhibiting these enzymes could potentially promote metastatic progression in various other cancers. Herein, we found that depletion of acetyl-CoA carboxylase 1 (encoded by ACACA), the enzyme responsible for the first and rate-limiting step of de novo fatty acid biosynthesis, facilitated epithelial-mesenchymal transition (EMT) and migration of PCa cells. This finding was validated in vitro through cell migration assays and in vivo using a metastatic model established by tail vein injection of ACACA-depleted cells into BALB/c nude mice. Additionally, depletion of ACACA activated the mitogen-activated protein kinase (MAPK)/extracellular signal-regulated protein kinases (ERK) pathway. Inhibition of the MAPK/ERK signaling pathway reduced EMT and migration in ACACA-depleted cells. Our study is the first to indicate targeting ACACA induces an "unexpected" escape program through activation of the MAPK/ERK signaling pathway in PCa, ultimately leading to EMT and metastasis. Therefore, we strongly recommend that the potential adverse effects of targeting ACACA or its derived therapeutic agents must be given extreme attention, especially in MAPK-related cancers.