Abstract Continental hydroclimate dynamics and its responses during the Middle Eocene Climatic Optimum (MECO, ∼40 Ma) remain largely unexplored. Here, we present high‐resolution multi‐proxy records from four East Asian lake basins that demonstrate precipitation, chemical weathering, and terrestrial input underwent multi‐phase changes during the MECO. Our results identify short‐eccentricity, precession, and half‐precession cycles as significant forcings on Eocene East Asian rainfall intensity, emphasizing their pivotal role in pacing hydroclimate evolution during the MECO. Our results also show that, before and during the early MECO, intensified precipitation enhanced chemical weathering and physical erosion, thereby increasing terrestrial input. At peak MECO, however, chemical weathering peaked despite reduced rainfall, suggesting a shift in the dominant weathering mechanism. We propose that extensive weathering and erosion during preceding warm and wet phases exposed large areas of fresh silicate surfaces, enabling temperature‐driven weathering during peak MECO. This process likely consumed substantial atmospheric CO2, ultimately terminating the event.