The development of high mobility organic laser semiconductors with strong emission is of great scientific and technical importance, but challenging. Herein, we present a high mobility organic laser semiconductor, 2,7‐diphenyl‐9H‐fluorene (LD‐1) showing unique crystallization‐enhanced emission guided by elaborately modulating its crystal growth process. The obtained one‐dimensional nanowires of LD‐1 show outstanding integrated properties including: high absolute photoluminescence quantum yield (PLQY) approaching 80 %, high charge carrier mobility of 0.08 cm2 V−1 s−1, Fabry‐Perot lasing characters with a low threshold of 86 μJ cm−2 and a high‐quality factor of ≈2400. Furthermore, electrically induced emission was obtained from an individual LD‐1 crystal nanowire‐based light‐emitting transistor due to the recombination of holes and electrons simultaneously injected into the nanowire, which provides a good platform for the study of electrically pumped organic lasers and other related ultrasmall integrated electrical‐driven photonic devices. [ABSTRACT FROM AUTHOR]