Myocardial ischemia-reperfusion (I/R) injury is a common complication following reperfusion therapy that involves a series of immune or apoptotic reactions. Studies have revealed the potential roles of miRNAs in I/R injury. Herein, we established a myocardial I/R model in rats and a hypoxia/reoxygenation (H/R) model in H9c2 cells and investigated the effect of miR-145-5p on myocardial I/R injury. After 3 h or 24 h of reperfusion, LVESP, EF, and FS were obviously decreased, and LVEDP was increased. Meanwhile, I/R induced an increase in myocardial infarction area. Moreover, a decrease in miR-145-5p and increase in NOH-1 were observed following I/R injury. With this in mind, we performed a luciferase reporter assay and demonstrated that miR-145-5p directly bound to NOH-1 3' UTR. Furthermore, miR-145-5p mimics decreased the levels of TNF-α, IL-1β, and IL-6 via OGD/R stimulation. Upregulation of miR-145-5p increased cell viability and reduced apoptosis accompanied by downregulation of Bax, cleaved caspase-3, cleaved PARP and upregulation of Bcl2. In addition, miR-145-5p overexpression increased SOD activity and reduced ROS and MDA content under OGD/R stress. Notably, NOH-1 could significantly abrogate the above effects, suggesting that it is involved in miR-145-5p-regulated I/R injury. In summary, our findings indicated that miR-145-5p/NOH-1 has a protective effect on myocardial I/R injury by inhibiting the inflammatory response and apoptosis.