Aurora kinases and protein kinase C (PKC) have been shown to be involved in different aspects of cancer progression. To date, no dual Aurora/PKC inhibitor with clinical efficacy and low toxicity is available. Here, we report the identification of compound <b>2e</b> as a potent small molecule capable of selectively inhibiting Aurora A kinase and PKC isoforms α, β1, β2 and θ. Compound <b>2e</b> demonstrated significant inhibition of the colony forming ability of metastatic breast cancer cells <i>in vitro</i> and metastasis development <i>in vivo</i>. <i>In vitro</i> kinase screening and molecular modeling studies revealed the critical role of the selenium-containing side chains within <b>2e</b>, where selenium atoms were shown to significantly improve its selectivity and potency by forming additional interactions and modulating the protein dynamics. In comparison to other H-bonding heteroatoms such as sulfur, our studies suggested that these selenium atoms also confer more favorable PK properties.