Circular RNAs (circRNAs) are a class of endogenous non-coding RNAs that play crucial roles in cancer progression and serve as miRNA sponges to regulate the expression of targeted genes. By analyzing the circRNA expression profile of gastric cancer (GC) with a circRNA microarray, we identify that circUBA1 is significantly upregulated in GC tissues and cell lines and was closely associated with advanced tumor-node-metastasis (TNM) stage and poor overall survival. Gain- and loss-of-function experiments showed that circUBA1 promoted the proliferation, migration, and invasion of GC cells in vitro and facilitated tumor growth and metastasis in vivo. Knockdown of circUBA1 led to significant downregulation of TEAD4 in Hippo signaling. Mechanistically, circUBA1 could serve as a sponge of miR-375 to upregulate TEAD4 expression levels, subsequently promoting GC progression. CircUBA1 acts as an oncogenic factor in GC via a novel circUBA1/miR-375/TEAD4 axis, thus providing potential biomarkers and therapeutic targets for the management of GC.