Although magnetotail bursty bulk flows (BBFs)/plasma bubbles are widely recognized as major plasma transport structures that provide particle acceleration and injection, their ionospheric signatures in energetic particles have not been established. In this study, we combine the ionospheric energetic proton flux (as a proxy to the equatorial pressure) and energetic electron loss-cone filling rate (as a marker of the equatorial magnetic field) to detect a rapid traversal from stretched to dipolarized field lines across the BBF channel. During a nonsubstorm episode when multiple flow bursts were observed in the plasma sheet, we show remarkable step-like increases of energetic proton flux (approaching 10³ in some events) observed in the middle of nightside auroral zone. We also conduct a high-resolution Rice Convection Model (RCM) simulation of a plasma-sheet bubble intrusion into the inner magnetosphere. Besides confirmation of the observed signatures, the simulation illustrates variability of the ionospheric signatures of bubbles and provides guidance in future studies of flow burst interactions.