Northwestern Pacific marine heatwaves have become increasingly persistent, with some events lasting multiple years. Traditional explanations focusing on local processes and tropical forcing cannot fully account for this unusual persistence. We identified a quasi-stationary Circumglobal Wave pattern as the primary driver of these long-duration events. This wavenumber-5 atmospheric pattern operates independently of ENSO and creates a self-reinforcing feedback loop: the wave pattern triggers Northwestern Pacific warming, which then strengthens the atmospheric pattern itself, extending heatwaves through summer and fall. Additionally, we discovered a trans-basin mechanism that sustains heatwaves through winter and spring. Summer warming in the northern North Atlantic, driven by the same Circumglobal Wave, persists into winter due to oceanic thermal inertia. This triggers a great-circle wave pattern that propagates back to the Northwestern Pacific, maintaining marine heatwaves during cold seasons. Analysis of observational data and climate model simulations reveals that these wave-ocean interactions have strengthened significantly since 1970, explaining why Northwestern Pacific marine heatwaves are becoming more frequent and persistent under ongoing climate change.