With the incorporation of Pd or Pt atoms, thiolated Ag-rich 25-metal-atom nanodusters were successfully prepared and structurally characterized for the first time. With a composition of [PdAg24(SR)(18)](2-) or [PtAg24(SR)(18)](2-), the obtained 25-metal-atom nanoclusters have a metal framework structure similar to that of widely investigated Au-25(SR)(18). In both clusters, a M@Ag-12 (M = Pd, Pt) core is capped by six distorted dimeric -RS-Ag-SR-Ag-SR- units. However, the silver-thiolate overlayer gives rise to a geometric chirality at variance to Au-25(SR)(18). The effect of doping on the electronic structure was studied through measured optical absorption spectra and ab initio analysis. This work demonstrates that modulating electronic structures by transition-metal doping is expected to provide effective means to manipulate electronic, optical, chemical, and catalytic properties of thiolated noble metal nanodusters.