Regulator of G-protein signaling 10 (RGS10) is an important member of the RGS family and produces biological effects in multiple organs. We used a genetic approach to study the role of RGS10 in the regulation of pathological cardiac hypertrophy and found that RGS10 can negatively influence pressure overload-induced cardiac remodeling. RGS10 expression was markedly decreased in failing human hearts and hypertrophic murine hearts. The extent of aortic banding-induced cardiac hypertrophy, dysfunction, and fibrosis in RGS10-knockout mice was exacerbated, whereas the heart of transgenic mice with cardiac-specific RGS10 overexpression exhibited an alleviated response to pressure overload. Consistently, RGS10 also inhibited an angiotensin II-induced hypertrophic response in isolated cardiomyocytes. Mechanistically, cardiac remodeling improvement elicited by RGS10 was associated with the abrogation of mitogen-activated protein kinase kinase 1/2-extracellular signal-regulated protein kinase 1/2 signaling. Furthermore, the inhibition of mitogen-activated protein kinase kinase-extracellular signal-regulated protein kinase 1/2 transduction abolished RGS10 deletion-induced hypertrophic aggravation. These findings place RGS10 and its downstream signaling mitogen-activated protein kinase kinase-extracellular signal-regulated protein kinase 1/2 as crucial regulators of pathological cardiac hypertrophy after pressure overload and identify this pathway as a potential therapeutic target to attenuate the pressure overload-driven cardiac remodeling.