Telomerase is now considered to be a valuable biomarker and therapeutic target in the diagnosis and treatment of cancerous diseases, which brings an urgent need in the development of fast and efficient telomerase detection strategies. Here, a new surface enhanced Raman scattering (SERS) based protocol using telomeric elongation controlled SERS (TEC-SERS) effect for the ultrasensitive telomerase detection is presented. The TEC-SERS protocol not only provides an unprecedented high sensitivity but also avoids laborious PCR procedures. The detection limit is ≈2–3 orders of magnitude lower than those of previously reported methods. This highly sensitive and straightforward TEC-SERS protocol can be developed as a routine telomerase detection method, which would greatly facilitate the telomerase based ultra-early diagnosis of malignant tumors and the fast screening of anti-cancer drugs.