A DNA-driven gold (Au) heterodimer for intracellular telomerase detection is fabricated. The highly biocompatible and intracellularly stable probe shows an active chiroptical property in the visible region, due to the scissor-like configuration formed by prolate nanoparticles. Importantly, the telomerase activity is specifically quantified using circular dichroism intensity in situ after internalization of the heterodimer into cancer cells. Moreover, the results clearly illustrate that this method has a remarkable linear range from 0.8 x 10(-12) to 32 x 10(-12) IU, and the limit of detection for telomerase activity is 1.7 x 10(-15) IU in a single HeLa cell. This strategy paves the way for chirality-based ultrasensitive detection of intracellular cancer markers.