Typhoon Soulik decayed rapidly via two‐way interaction with the northern East China Sea (NECS), the extratropical shelf region, before landing on the Korean Peninsula on August 23, 2018. In the NECS, where the water column is strongly stratified with warm surface and cold subsurface waters, a large cold wake emerged with intense sea surface cooling (SSC), which is primarily caused by vertical mixing in the water column. This abrupt SSC rapidly increased the downward enthalpy flux, mostly in the form of latent heat flux. The slow translation speed of Typhoon Soulik and strong thermal stratification in the region transferred its energy into the ocean, as the typhoon had a long residence time over the wake, and consequently led to rapid decay with energy loss to typhoon intensity ratio of ‐4.4 ± 1.0 hPa (kJ cm‐2)‐1.