AbstractNext‐generation high‐security cryptography and communication call for nondeterministic generation and efficient authentication of unclonable bit sequences. Physical unclonable functions using inherent randomness in material and device fabrication process have emerged as promising candidates for realizing one‐way cryptographic systems that avoid duplication and attacks. However, previous approaches suffer from the tradeoffs between low‐efficiency fabrication and complicated authentication. Here, all‐photonic cryptographic primitives by solution printing of organic nanolaser arrays with size‐dependent dual lasing emission are reported. The stochastic distribution of organic solution into discrete capillary bridges, triggered by high‐rate solvent evaporation, on a periodic topographical template yields organic single crystals with regulated position, alignment, and random size, which ensures high entropy. Stimulated emission from different vibrational sublevels and the intrinsic self‐absorption effect permit size‐dependent dual‐wavelength lasing emission at wavelengths of 660 and/or 720 nm, which can be efficiently encoded into quaternary cryptographic keys with high reliability. High entropy, solution‐processed programming and all‐photonic authentication of random organic nanolaser arrays facilitate their cryptographic implementation in secure communication with high throughput, efficiency, and low cost.