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Dysregulated oncogenic serine/threonine kinases play a pathological role in diverse forms of malignancies, including multiple myeloma (MM), and thus represent potential therapeutic targets. Here, we evaluated the biological and functional role of p21-activated kinase 4 (PAK4), and its potential as a new target in MM for clinical applications. PAK4 promoted MM cell growth and survival via activation of MM survival signaling pathways, including the MEK-ERK pathway. Furthermore, treatment with orally bioavailable PAK4 allosteric modulator (KPT-9274) significantly impacted MM cell growth and survival in a large panel of MM cell lines and primary MM cells alone and in the presence of bone marrow microenvironment. Intriguingly, we have identified FGFR3 as a novel binding partner of PAK4 and observed significant activity of KPT-9274 against t(4;14)-positive MM cells. These data support PAK4 as an oncogene in myeloma, and provide the rationale for the clinical evaluation of PAK4 modulator in myeloma.