A two-phase solidification model coupling mold electromagnetic stirring (M-EMS) is used to investigate the initial solidification in the mold region of billet continuous casting. One novelty of this numerical study is to quantify how the M-EMS induces primary and secondary flows, interacting with the jet flows coming from the submerged entry nozzle, and how those flows further influence the dissipation of superheat and the initial solidification. The role of the M-EMS in speeding up the superheat dissipation in the mold region, known from previous studies and casting practices, is quantitatively verified. Additionally, some new knowledge regarding the M-EMS is found. The total heat transfer rate from the strand surface to the water-cooled copper mold is not affected by the M-EMS; with the M-EMS, the superheat effect on the solid growth can only be detected in the out-of-the-mold region, while the shell growth inside the mold region is quite independent of the superheat; a strong M-EMS tends to accelerate the growth of the solid shell in the mold region, but delays its growth in the secondary cooling zones. The aforementioned new findings may only be valid for the case of the current billet casting, to be confirmed for other casting formats/parameters.