We propose a multi-voltage (multi-Vdd) variable pipeline router to reduce the power consumption of Network-on-Chips (NoCs) designed for chip multi-processors (CMPs). Our multi-Vdd variable pipeline router adjusts its pipeline depth (i.e., communication latency) and supply voltage level in response to the applied workload. Unlike dynamic voltage and frequency scaling (DVFS) routers, the operating frequency is the same for all routers throughout the CMP; thus, there is no need to synchronize neighboring routers working at different frequencies. In this paper, we implemented the multi-Vdd variable pipeline router, which selects two supply voltage levels and pipeline modes, using a 65nm CMOS process and evaluated it using a full-system CMP simulator. Evaluation results show that although the application performance degraded by 1.0% to 2.1%, the standby power of NoCs reduced by 10.4% to 44.4%.