Abstract The inner radiation belt (L* < 3) has long been considered an impenetrable barrier to ultra‐relativistic electrons. Here we show that this barrier can be breached under extreme space weather conditions. Using continuous near‐equatorial observations from the Arase satellite, we show that the May 2024 superstorm rapidly generated multi‐MeV electrons deep inside the inner magnetosphere. Phase space density profiles reveal the development of a local maximum at L* ∼ 3, providing evidence that local in situ acceleration established multi‐MeV electron source before supplying inward and outward radial diffusion. Simultaneous observations of intense chorus waves under a strongly depleted plasma region, maintained by enhanced convection and a negative ionospheric storm, are consistent with chorus‐driven local acceleration. These findings demonstrate that local acceleration can establish a multi‐MeV electron source inside the impenetrable barrier under extreme space weather conditions.