Abstract Low-frequency noise (LFN) characteristics of semiconductor devices pose a significant importance for understanding their working principle, particularly concerning material imperfections. Accordingly, substantial research endeavors have focused on characterizing the LFN of devices. However, the LFN characteristics of the ambipolar transistors have been rarely demonstrated. Herein, we investigate the effects of ambipolar carrier transport and CYTOP-induced p-type doping on low-frequency noise characteristics of MoTe2 transistors. The source of the 1/f noise differs between the n-type (electron transport) and p-type (hole transport) modes. Notably, the influence of contact resistance is more pronounced in the n-type mode. CYTOP doping suppresses the n-type mode by introducing hole doping effects. Furthermore, CYTOP doping mitigates the impact of contact resistance on excess noise.