Herein, two simultaneous replacement reactions were explored to prepare a variety of bimetallic dendrites (AgCu, AgPd, AuPd, CuAu, CuPt and CuPd) in one step, using commercial Mg powder as a sacrificial metal to reduce the bimetallic precursors in aqueous solution. We demonstrate in detail how the morphologies and compositions of the bimetallic dendrites are affected by factors such as the potential difference between the metal redox couples, molar ratios of precursors, ligands, reaction times and total precursor concentrations, taking dendritic AgCu as an example. In addition, monometallic Ag and Cu dendrites were also prepared for comparison. The application of these prepared dendrites as high performance catalysts for the reduction of 4-nitrophenol in aqueous solution at room temperature was further explored. The order of activity CuPd > CuPt > CuAu > Cu > Ag₁Cu₁ > Ag₃Cu₁ > AuPd > Ag₁Cu₃ > AgPd > Ag was established for the prepared dendrites based on normalized kinetic parameters according to our proposed formula.