The requirement for lithium-ion batteries is rising sharply in recent years due to rapid development of electric vehicles and new energy storage. However, this increase in number of lithium-ion batteries also leads to the production of a significant number of spent batteries. Considering the potential environment pollution and waste of resources, it is absolutely imperative to recover these spent lithium-ion batteries. Conventional direct regeneration method always undergoes a slow heating rate and prolonged calcination process, which consume high energy and time. Herein, we presented an efficient, low-cost and ultrafast regeneration strategy for rapid regeneration of the spent LiFePO4 in only 20 s. Compared of traditional method, this ultrafast method consumes less energy and takes shorter time. As a result, the lithium is completely replenished and the structure of LiFePO4 is well repaired, and it demonstrates excellent initial capacity of 152 mAh g−1 at 0.1C. Furthermore, RLFP-800 exhibits a good rate performance and long-cycling stability (400 cycles at 2C without capacity recession). It is expected that this rapid regeneration strategy can be developed for practical spent LiFePO4 regeneration at low cost.