Abstract The Madden‐Julian Oscillation (MJO), a crucial source of subseasonal predictability, experiences El Niño‐Southern Oscillation (ENSO) modulation whose impacts vary by event type. Using an analog‐based methodology that incorporates a history of dynamical system evolution and epsilon‐based neighborhoods, we quantify how Eastern‐Pacific (EP) and Central‐Pacific (CP) ENSO events distinctly regulate the predictability limit of the real‐time multivariate MJO (RMM) index. Results unravel a remarkable 9‐day predictability advantage during EP La Niña over EP El Niño, attributable to stronger amplitude and prolonged persistence of initial signals, particularly during RMM phases 1–2 and 7–8. In contrast, how CP ENSO modulates the predictability is phase‐dependent, owing to the balance between MJO signal strength and atmospheric high‐frequency noises. Therefore, the overall predictability of the RMM index remains similar across CP ENSO states. These findings underscore the need to jointly account for the initial RMM phase and ENSO type in improving subseasonal forecasting.