Aim To investigate whether exogenous hydrogen sulfide (H₂S) protects against high glucose (HG)-induced H9c2 cardiomyocyte injury and inflammation response by inhibiting reactive oxygen species (ROS)-Toll-like receptor 4 (TLR4) pathway. Methods Cell counter kit-8 (CCK-8) assay was used to measure the cell viability, the activity of lactate dehydrogenase (LDH) in the culture medium was measured with commercial kits, the levels of interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α) were detected by ELISA, the number of apoptotic cells was observed by Hoechst 33258 nuclear staining followed by photofluorography, the expression levels of TLR4 and Cleaved Caspase 3 were determined by Western blot, the intracellular level of ROS was detected by 2’,7’-dichlorfluorescein-diacetate (DCFH-DA) staining followed by photofluorography, mitochondrial membrane potential (MMP) was examined by Rhodamine 123 staining followed by photofluorography. Results After H9c2 cardiac cells were exposed to 35 mmol/L glucose (HG) for 24 h, the expression level of TLR4 was significantly increased. Pre-treatment of the cells with 1000 μmol/L N-acetyl-L-cysteine (NAC) for 60 min or with 400 μmol/L sodium hydrogen sulfide (NaHS) for 30 min before HG exposure considerably attenuated the up-regulation of TLR4 expression level induced by HG. HG induced considerable injuries and inflammatory response, leading to a decrease in cell viability, increases in the activity of LDH, the number of apoptotic cells, the expression of Cleaved Caspase 3, ROS generation, MMP loss as well as the secretion levels of IL-1β and TNF-α. Pre-treatment of the cells with 400 μmol/L NaHS for 30 min before HG exposure or co-treatment of the cells with 30 μmol/L TAK-242 (an inhibitor of TLR4) and HG for 24 h obviously reduced the above injuries and inflammatory response induced by HG. Conclusion Exogenous H₂S protects against the HG-induced H9c2 cardiomyocyte injury and inflammation response by inhibiting ROS-TLR4 pathway.