Monitoring system-on-chip performance under process, voltage, and temperature (PVT) variations is very challenging, especially when the parasitic effects dominate the whole chip performance in advanced process nodes. Most of the previous works presented the performance monitoring methodologies based on known/predicted candidates of critical paths under different operating conditions. However, those methodologies may fail when the critical path is misrecognized or mispredicted. This paper proposes a novel machine-learning based chip performance monitoring methodology to accurately match the chip performance without requiring the information of critical paths under various PVT conditions. The experimental results based on measured chip performance show that the proposed methodology can achieve 98.5% accuracy in the worst case under wide-range PVT variations.