Given the increasing environmental and energy issues, materials with the ability to repair themselves following damage are highly desirable because this self-healing property can prolong the lifespan of materials and reduce replacement costs. Host–guest assemblies are a powerful approach to create supramolecular materials with versatile functions. Here, a new mode of radical polymerization is demonstrated which is achieved via magnetocaloric effect to fabricate novel host–guest supramolecular gels within 5 min. The resulting gels can repair themselves spontaneously when damaged, without the assistance of any external stimuli, and possess great mechanical strength. Moreover, the Fe3O4-doped supramolecular gels show accelerated self-healing (from 24 h to 3 h) under an applied magnetic field, which is attributed to the synergy between host–guest healing and a magnetocaloric effect. This strategy might open a promising avenue for accelerating the use of host–guest assemblies to rapidly build robust materials.