For cytokinesis, the physical division of two nascent cells, actomyosin networks drive cleavage furrow ingression. During this process, network contractility is promoted through myosin phosphorylation mediated by Rho kinase (Rok) and reversed by myosin phosphatase. Cleavage of the early Drosophila embryo involves incomplete cytokinesis to maintain syncytial organization. Furrows ingress as lateral membranes, but actomyosin networks at their basal tips do not constrict to close the base of the cells. How myosin activity affects membrane ingression remains unclear. Previous work suggested that myosin is not essential for furrow ingression, whereas other studies indicated that actomyosin networks are actively inhibited to prevent full cell division. To investigate whether myosin is involved in furrow ingression, we perturbed Rok by RNAi. We found that myosin is lost from furrow membranes and furrows failed to ingress when Rok was severely depleted. Myosin regulatory light chain (MRLC) RNAi mimics the defects seen with Rok-RNAi, indicating myosin is required for proper furrow organization. To test the role of myosin de-phosphorylation, we targeted the myosin binding subunit of myosin phosphatase (Mbs) by RNAi. Loss of Mbs increased myosin accumulation at the base of furrows and induced constriction at these sites. As a result, basal membranes closed abnormally and impinged on nuclei. To confirm the effects were due to excessive myosin activity, we also overexpressed Rok or phosphomimetic-MRLC and observed similar basal membrane closure, indicating Mbs keeps myosin activity in check during furrow ingression. To dissect how myosin activity is controlled by this phosphor-regulation, we compared the furrow localization of myosin, Rok, and the catalytic subunit of myosin phosphatase, Flapwing (Flw). The cortical level of all three proteins changed over the cell cycle. As new cleavage furrows formed, levels of all three protein gradually increased on the furrow membrane, with enrichment at their basal tips Together, these data suggest that syncytial embryo cleavage depends on myosin activity that is not too low or too high, a Goldilocks effect, and that the proper range of activity is set locally by the counteracting activities of Rok and myosin phosphatase.