Impacts of climate change on heat budget in the Eastern China Seas (ECSs) are estimated under the historical, RCP4.5 and RCP8.5 scenarios using an atmosphere-ocean coupled regional climate model system (REMO/MPIOM). The results suggest that the recent and future ocean warming over the ECSs is linked overall to an increased oceanic heat transport by currents, which is partly compensated by the air-sea heat exchange. The Taiwan Strait is the major source of oceanic heat into the ECSs, whereas the shelf break section (SBS) acts as a heat sink. An increased net oceanic heat transport into the ECSs is projected under both considered RCP scenarios, mainly resulting from a reduction of the outward heat transport through the SBS. The mean relative contribution of SBS to the oceanic heat transport thus decreases by 4%–5% under both RCP scenarios, relative to historical run. Regarding the surface air-sea exchange, the heat loss caused by thermal radiation, latent and sensible heat in the ECSs exceeds the heat gain achieved by solar radiation. Under the RCP scenarios, warmer SST and stronger surface wind will enhance the upward latent heat flux, eventually leading to a more pronounced heat loss from the ECSs. The mean relative contributions of the latent heat flux to the air-sea heat exchange notably increases by 2%–3% under both projection scenarios, relative to historical run. Taking into account all components of the ECSs heat balance, we deduce that the increased horizontal heat transport will enhance the surface evaporation over the ECSs under future warming.