Organic porous fluorescent materials created by supramolecular noncovalent synthesis can be developed for fluorescent sensing applications. In this study, we report a noncovalent synthesis of a near-infrared porous fluorescent crystal and its solvent vapor-responsive fluorescence change. The donor–acceptor type phenothiazine–thiadiazolopyridine dye emits near-infrared fluorescence at 727 nm in the as-prepared state. The near-infrared emission band is shifted to 792 nm upon application of mechanical grinding and subsequent chloroform vapor-fuming. The resulting fumed sample has a porous crystal structure with a pore size larger than 5.75 A. The electron-donating phenothiazine and electron-accepting thiadiazolopyridine moieties are closely one-dimensionally stacked through multiple noncovalent interactions, and the created one-dimensional architectures are two-dimensionally organized through an alternative arrangement of the phenyl groups on the phenothiazine rings, resulting in a three-dimensional porous structure. This near-infrared porous fluorescent crystal responds to the polarity difference of solvent vapors (from nonpolar hexane to polar methanol) incorporated inside the pore site, providing fluorescence wavelength and intensity changes.