The Lysine-specific demethylase 1, KDM1A/LSD1, plays a central role in the regulation of Pol II transcription through the removal of the activation mark (mono- and dimethyl lysine 4 of histone H3). LSD1 is often deregulated in human cancers, and it is frequently overexpressed in human solid cancers and leukemia. LSD1 regulates the epithelial mesenchymal transition (EMT) in epithelial cells, i.e., the ability to transition into mesenchymal cells, to lose homotypic adhesion and to acquire migratory capacity. From its initial discovery as a component of the Snail complex, multiple studies highlighted the causative role of LSD1 in cell invasiveness and EMT, describing its direct involvement in different molecular processes through the interaction with specific partners. Here we present an overview of the role of LSD1 in the EMT process, summarizing recent findings on its emerging functions in cell migration and invasion in cancer.