The impact of work-function variation (WFV) on performance of an inversion-mode (IM) dual-metal gate (DMG) fin field-effect transistor (FinFET) was investigated for the first time. The statistical fluctuations induced by WFV on the threshold-voltage (VTH), transconductance (gm), and subthreshold slope (SS) were demonstrated and estimated utilizing a 3D technology computer-aided design (TCAD) simulator. We found that the performance variations of the DMG FinFET were affected by two different metals near the drain and near the source, respectively. Additionally, this effect of the two metals on the channel was not monotonic with the length of the channel of their own control. Our work fills a gap in the study of WFV for a DMG IM FinFET and provides a reference for optimizing the distribution of the two metals.