Well-defined crystalline condensed superstructures of conjugated molecules are required for light-emitting optoelectronic devices. Similar to symmetry breaking in nature, stereoisomerism can programmatically and extraordinarily control molecular crystallization and provide access to unexpected optoelectronic behaviors. Here, we demonstrated supramolecular chiral oligofluorenols (2O8-DPFOH-SFX) with a hierarchical ordered structure and ultrastable crystalline-enhanced emission by controlling the molecular stereoisomerism. The raceme displays a highly ordered and uniform structure with molecular-level orientation, but no transition was observed for the mesomer. This well-defined architecture shows unique robust and ultrastable crystalline-enhanced emission with PLQE 90% higher than that of the pristine one. Finally, the nanosheet laser with deep-blue emission was manufactured, attributed to the 0–1 vibronic band of the quasi-planar conformation. The stereoisomerism-property relationship of conjugated aromatic molecules can serve as a model, offering a general guideline for optimizing the morphology and alignment of organic semiconductors for optoelectronic applications.