Transcription factor AP-$2{alpha}$ involves in the process of mammalian embryonic development and tumorigenesis. Many studies have shown that AP-$2{alpha}$ functions in association with other interacting proteins. In a two-hybrid screening, the regulatory subunit ${eta}$ of protein casein kinase 2 ($CK2{eta}$) was identified as an interacting protein of AP-$2{alpha}$; we confirmed this interaction using in-vitro GST pull-down and in-vivo co-immunoprecipitation assays; in an endogenous co-immunoprecipitation experiment, we further found the catalytic subunit ${alpha}$ of protein casein kinase 2 ($CK2{alpha}$) also exists in the complex. Phosphorylation analysis revealed that AP-$2{alpha}$ was phosphorylated by CK2 kinase majorly at the site of Ser429, and such phosphorylation could be blocked by CK2 specific inhibitor 4,5,6,7-tetrabromobenzotriazole (TBB) in a dose-dependent manner. Luciferase assays demonstrated that both $CK2{alpha}$ and $CK2{eta}$ enhanced the transcription activity of AP-$2{alpha}$; moreover, $CK2{eta}$ increased the stability of AP-$2{alpha}$. Our data suggest a novel cellular function of CK-2 as a transcriptional co-activator of AP-$2{alpha}$.