The main objective of this investigation is to improve the photoluminescent performance of existing Zn2SiO4:Mn phosphors by adding a new co-dopant. The candidate co-dopants adopted in the present investigation are confined to substituents for the Zn site. In this context, the co-doping effect of Mg and/or Cr upon emission intensity and decay time was studied in the present investigation. The co-dopants incorporated into the Zn2SiO4:Mn phosphors are believed to alter the internal energy slate so that the change in emission intensity and decay time could be expected. Both Mg and Cr have a favorable influence on photoluminescent properties, in particular, Mg enhances the intensity of manganese green emission and Cr shortens the decay time. The enhancement in emission intensity of Zn2SiO4:Mn, Mg phosphors was interpreted by taking into account the result from the DV-Xa embedded cluster calculation. On the other hand, the energy transfer between Mn and Cr ions was found to be responsible for the shortening of decay time in Zn2SiO4:Mn,Cr phosphors.