The highly sensitive and quantitative biodetection of intracellular telomerase is challenging. A DNA-driven nanoparticle self-assembling pyramid encoding a Raman reporter (Cy5) is reported that detects telomerase in live cells. In the presence of the target, the telomerase primer is extended and the inner DNA chain is replaced, leading to the reduction in the surface-enhanced Raman scattering (SERS) signal and the simultaneous recovery of the fluorescent signal. The SERS signal has a linear range for the detection of telomerase in situ of 1 x 10(-14) to 5 x 10(-11) IU, with a limit of detection of 6.2 x 10(-15) IU. The fluorescent signal is used to confirm the intracellular telomerase activity, demonstrating the efficacy of the designed pyramid probe. This biosensing strategy provides a reliable and ultrasensitive protocol for the quantification of biomarkers in living cells.