Wagner defeated lawyer Laura Ellsworth and businessman Paul Mango in the primary that was noted for the harsh attacks between Wagner and Mango.
Wagner, who was endorsed by the state GOP, currently holds a 44-36 lead over Mango.
Wagner spent millions of his own dollars to win the primary.
He also selected Berks County attorney Jeff Bartos as his informal running mate. Bartos defeated Washington County Commissioner Diana Irey Vaughan, former Bellevue Councilwoman Kathy Coder, and pro-life activist Peg Luksik in the separate LG primary.