A label-free and turn-on fluorescent ATP detection is reported with a ss-DNA aptamer as the recognition part, an AIE molecule as the fluorescent probe, and water-soluble carbon nanotubes as the selective part with the fluorescent quenching effect. The specific binding between the aptamer and target ATP makes the aptamer released from the water-soluble carbon nanotubes. As a consequence, the AIE-active probes, attaching on the surface of ss-DNA, recover to give fluorescence and present a strong emission. The introduction of water-soluble carbon nanotubes allows creating low background fluorescence, which is a great advantage for ATP detection.