AbstractNature utilizes non‐equilibrium self‐assembly to achieve remarkable functions. Although such systems have been synthesized, this class of assembly is only sparsely explored in innovative materials with life‐like functions. Here, we report transient nanoparticles driven by adenosine triphosphate and their applications on the self‐erasable and rewritable security labels. We show that the lifetime of transient nanoparticles can be tuned from a few minutes to hundreds of minutes through adjusting concentrations of the components. By integrating the transient nanoparticles into hydrogels, we achieve self‐erasable and rewritable labels with time‐ and space‐encoded information encryption. Notably, a smart Morse code is implemented by programming the hydrogel labels in a spatiotemporal manner. This work provides an emerging material involving transient nanoparticles for information encryption, further accelerating the explorations of the new type information encryption materials.