Optogenetics allows for the study of signaling pathways during a variety of cellular processes. Here we use subcellular optogenetics to study the role of vesicular trafficking in cytokinesis. Optogenetically activating RhoA in the cell midline induces cytokinesis and intercellular bridge formation. RhoA activates the actomyosin contractility network, leading to retrograde plasma membrane flow, localized decrease in membrane tension, and increase in endocytosis at the cell middle. Endocytic vesicles and trafficking proteins localize to the intercellular bridge. Perturbation of these proteins inhibits furrow formation. Thus polarized endocytosis and exocytosis in the first steps of cytokinesis provide new membrane to the middle of the cell and allow the cell to build the cleavage furrow and intercellular bridge.