This study investigates ocean warming and its uncertainty from 1961 to 2022 using a large-ensemble reanalysis system. The results indicate a 62-year warming of 0.43 ± 0.08 W m⁻², with a statistically significant acceleration rate of 0.15 ± 0.04 W m⁻² dec⁻¹, peaking at high latitudes. The global ocean area that reached its maximum yearly ocean heat content (OHC) in 2022 was 11.6%, almost doubling any previous year. Regional uncertainties are highest in the tropics, while global uncertainties are about 40% and 15% before and after the mid-2000s, respectively. The uncertainty in regional trends is primarily influenced by observation calibration and sea surface temperature data uncertainty. The study also compares the reanalysis results with other datasets and objective analyses, confirming the reliability of the reanalysis system. The findings highlight the importance of understanding and quantifying uncertainties in ocean warming assessments for monitoring Earth's energy budget and climate change.This study investigates ocean warming and its uncertainty from 1961 to 2022 using a large-ensemble reanalysis system. The results indicate a 62-year warming of 0.43 ± 0.08 W m⁻², with a statistically significant acceleration rate of 0.15 ± 0.04 W m⁻² dec⁻¹, peaking at high latitudes. The global ocean area that reached its maximum yearly ocean heat content (OHC) in 2022 was 11.6%, almost doubling any previous year. Regional uncertainties are highest in the tropics, while global uncertainties are about 40% and 15% before and after the mid-2000s, respectively. The uncertainty in regional trends is primarily influenced by observation calibration and sea surface temperature data uncertainty. The study also compares the reanalysis results with other datasets and objective analyses, confirming the reliability of the reanalysis system. The findings highlight the importance of understanding and quantifying uncertainties in ocean warming assessments for monitoring Earth's energy budget and climate change.