A vehicle body front reinforcement assembly includes: a front side beam connected to a front of a dash panel; a side sill connected to a side end portion of a floor panel; and a torque box extending from the dash panel to the side end portion of the floor panel and connecting a rear end of the front side beam to a front end of the side sill, wherein the side sill includes: a side sill coupler coupled to a rear end of the torque box; and a side sill extension connected to a rear end of the side sill coupler and extending towards the rear of a vehicle, and wherein the side sill coupler is made of a material having a lower tensile to strength than the material of the side sill extension.