The pathophysiology of heart failure with preserved ejection fraction (HFpEF) remains unclear, making the diagnosis and treatment challenging. Cardiac oxidative and nitrative stress are strongly implicated in the pathogenesis of HFpEF. Herein, we present a unique three-channel fluorescent probe for evaluating cardiac oxidative and nitrative stress in HFpEF by simultaneous detection of NO and GSH. The probe exhibits a native green fluorescence (probe channel), while the presence of GSH and NO can sensitively turn the native green fluorescence into red fluorescence (GSH channel) and near-infrared fluorescence (NO channel), respectively. The probe clearly reveals that both GSH and NO levels are upregulated in cardiomyocytes and heart tissue with HFpEF. Moreover, it uncovers that the enhancement in NO and GSH levels are closely associated with increased level of iNOS (inducible nitric oxide synthase) and activation of the Keap1 (Kelch-like ECH-associated protein 1)/Nrf2 (nuclear factor erythroid 2–related factor 2)/ARE (antioxidant response element) signaling pathway in cardiomyocytes, respectively. This work proposes a promising approach for distinguishing normal heart and HFpEF heart by in vivo noninvasive imaging of both GSH and NO, and greatly contributing to the improvement of the diagnosis and treatment of HFpEF.