Functionalized single-walled carbon nanotube (SWCNT)-based chemiresistors are reported for a highly robust and sensitive gas sensor to selectively detect cyclohexanone, a target analyte for explosive detection. The trifunctional selector has three important properties: it noncovalently functionalizes SWCNTs with cofacial $π$-$π$ interactions, it binds to cyclohexanone via hydrogen bond (mechanistic studies were studied), and it improves the overall robustness of SWCNT-based chemiresistors (e.g., humidity and heat). The authors' sensors produced reversible and reproducible responses in <30 s to 10 ppm of cyclohexanone and displayed an av. theor. limit of detection (LOD) of 5 ppm. [on SciFinder(R)]