Preserving genome integrity is important for cell survival. Replication stress during S- phase can compromise genome integrity, as it delays replication into mitosis. The presence of underreplicated DNA in mitosis can cause severe issues when the DNA is segregated to the two emerging daughter cells and may transition into DNA damage. We previously described that chicken TopBP1 is recruited to foci on chromatin in early mitosis and is important for minimizing the transmission of damaged DNA to daughter cells. Specifically, we showed that chicken TopBP1 is required for recruitment of the nuclease scaffold SLX4, which is an important factor to promote repair of underreplicated DNA in mitosis, and that the absence of TopBP1 in mitosis induced focus formation of the DNA damage marker, 53BP1, in G 1 cells. Whether this protective function of TopBP1 is conserved in humans and how TopBP1 is recruited to underreplicated DNA in mitosis remained elusive. Therefore, in this study, we set out to identify factors that influence the recruitment of TopBP1 to foci in mitosis. Furthermore, we aimed at identifying the role(s) of TopBP1 in promoting repair of replication-associated lesions to the DNA in mitosis. Here, we show that human TopBP1 localize to foci induced by underreplicated DNA in mitosis. At these sites, TopBP1 is recruited in a complex with the PP2A inhibitor, CIP2A, and SLX4 to promote mitotic DNA synthesis (MiDAS). Mutating key residues in TopBP1 (K704) or SLX4 (T1260 or SIM1-3) abolished the recruitment of SLX4 to TopBP1 foci and caused a reduction in MiDAS and elevated levels of 53BP1 foci in G 1 cells. Together, this indicates that TopBP1 preserves genome integrity in mitosis after replication stress. Additionally, we performed two high-content drug screens, where we identified several candidate regulators of TopBP1 recruitment in mitosis. Among the candidate regulators, the mitotic kinases Aurora and CDK1 were hits in both chicken and human cell lines, indicating pathway conservation between birds and humans. To summarize, we have identified potential regulators of TopBP1 in mitosis and we have established TopBP1 as a key factor in promoting replication of underreplicated DNA in mitosis. In a cancer perspective, targeting the recruitment of TopBP1 in mitosis could serve as a novel therapeutic approach to target highly replicative cancers that likely rely on the MiDAS pathway to support uncontrolled growth and tumorigenesis.