Abstract: To remedy the lack of long-term, high-resolution marine heatwaves (MHWs) data and to provide an earlier, temporally continuous and consistent global record, we developed a global high-resolution marine heatwave dataset spanning 1969—2018 based on high-resolution daily sea surface temperature (SST) from the LASG/IAP Climate System Ocean Model (LICOM) and the Optimum Interpolation Sea Surface Temperature (OISST) product. MHW events were identified using a daily percentile-threshold method. The performance of LICOM in reproducing MHWs was evaluated using correlation coefficients, spatial pattern comparisons, and time-series analyses, followed by an examination of the spatiotemporal characteristics and seasonal variability of MHWs and their links to mesoscale eddies and the El Ni?o–Southern Oscillation (ENSO). The results indicate that LICOM reproduces the spatial pattern of MHW intensity and the interannual variability of MHW frequency, but systematically overestimates MHW frequency and duration. MHW frequency exhibits a significant increasing trend during boreal summer, dominated by contribution from mid-latitude oceans where MHW intensity is generally higher. Eddy-active regions (e.g., the Kuroshio Extension and the Gulf Stream) display markedly higher MHW intensity, frequency, and duration than eddy-inactive regions. The global monthly mean MHW frequency during El Ni?o is 34.38% higher than during La Ni?a. This dataset provides long-term, high-resolution data support for investigating MHW variability and its links to mesoscale eddies and ENSO, and offers a reference for bias diagnosis in high-resolution ocean models and for improving simulations of extreme events.