Abstract Coastal decadal sea level anomalies (SLAs) in the U.S. east coast (USEC) play a critical role in modulating coastal flooding frequency, yet relative influences of tropical versus extratropical climate modes over the North Atlantic remain unresolved. By integrating observations, simulations from simplified dynamical models and climate models, we show that remote forcings drive the most USEC decadal SLAs since 1950, with approximately half of this signal transmitted via westward‐propagating Rossby waves. Notably, the tropical climate modes, the Atlantic Meridional Mode (AMM) and Atlantic Nino, exert comparable remote influences as the extratropical climate modes in the USEC. We identify a key mechanism that AMM‐related wind and buoyancy forcings act constructively in the northwest Atlantic, amplifying decadal SLAs in the north USEC. Our findings reveal that tropical Atlantic variability is an important, yet previously underappreciated, driver of regional sea level, underscoring its critical role in decadal predictions and flood risk assessments.