TThe Aurora kinases comprise an evolutionarily conserved protein family that is required for a variety of cell division events including spindle assembly, chromosome segregation and cytokinesis. Emerging evidence suggests that a subset of Aurora substrates, once phosphorylated, can enhance Aurora kinase activity. Our previous work revealed that the C. elegans Tousled-like kinase, TLK-1, is a substrate and activator of the AIR-2 Aurora B kinase in vitro and that partial loss of TLK-1 enhances the mitotic defects of an air-2 mutant. However, given that these experiments were performed in vitro and with partial loss of function alleles in vivo, a necessary step forward in our understanding of the relationship between the Aurora B and Tousled kinases is to prove that TLK-1 expression is sufficient for Aurora B activation in vivo. Here, we report that heterologous expression of wild- type and kinase-inactive forms of TLK-1 suppress the lethality of temperature-sensitive mutants of the yeast Aurora B kinase Ipl1. Moreover, kinase-dead TLK-1 associates with and augments the activity of Ipl1 in vivo. Together, these results provide critical and compelling evidence that Tousled has a bonafide kinase-independent role in the activation of Aurora B kinases in vivo.