An impregnated fiber tow comprising multiple unitary graphene-based continuous graphitic fibers impregnated with a matrix material, wherein at least one of the continuous graphitic fibers comprises at least 90% by weight of graphene planes that are chemically bonded with one another having an inter-planar spacing d002 from 0.3354 nm to 0.4 nm as determined by X-ray diffraction and an oxygen content less than 5% by weight, wherein the graphene planes are parallel to one another and parallel to a fiber axis direction and the graphitic fiber contains no core-shell structure, has no helically arranged graphene domains or domain boundary, and has a porosity level less than 5% by volume.