${eta}$-Catenin is an evolutionally conserved protein which orchestrates myriad biological processes by regulatingWnt signaling and cell adhesion. The importance of the dual roles of ${eta}$-catenin protein (signaling and structural) is highlighted throughout the development and adult life of all metazoan animals. ${eta}$-Catenin is located in the cadherin-based adherent junctions in the plasma membrane of epithelial cells; uponWnt activation, it accumulates and translocates to the nucleus in order to activate transcription. Thus, mutations in ${eta}$-catenin and the components of the Wnt signal transduction pathway underline the aberrant activation of Wnt/${eta}$-catenin signaling in human diseases and cancers. In this review, we briefly summarize the core functions of ${eta}$-catenin relevant to Wnt signaling and adhesion and introduce the additional and novel role of ${eta}$-catenin related to the regulation of RiboNucleoAcid (RNA) metabolism. Such multiple functions of ${eta}$-catenin can be understood by examining its structure and complex with the plethora of interacting proteins. Also, molecular evolution analysis has been used to understand the origin of multifunctionality of ${eta}$-catenin.We will also discuss the newly identified role of ${eta}$-catenin as an RNA-binding protein and as a regulator of RNA stability and splicing. It is hoped that future research will shed light on any unexpected findings by clarifying the RNA-mediated mechanism of ${eta}$-catenin and the implication to Wnt-regulated pathogenesis.