The Si addition has a great impact on the glass forming ability of Cu50Zr43Al7 bulk metallic glass (BMG). To investigate the effective role of Si doping on the crystallization behavior of the BMGs, crystallization transformation kinetics of Cu50Zr43Al7 and (Cu50Zr43Al7)99Si1 BMGs were explored at non-isothermal and isothermal conditions by differential scanning calorimetry (DSC) experiments. The Si doping enhances the activation energy of crystallization transformation (resistance against crystallization) under both thermal circumstances. Avrami exponents were obtained by employing the Johnson–Mehl–Avrami–Kolmogorov (JMAK) model. In the isothermal regime, Avrami exponents in both BMGs were 2.2, which reveals that the dominant mechanism of crystallization is the three-dimensional growth with a decreasing nucleation rate of crystals. The time–temperature–transformation or TTT diagram displayed that minor alloying of Si displaced the crystallization transformation to elevated temperatures and longer incubation times.