The development of new polymer composites with conductive and magnetic fillers that are compatible with additive manufacturing (AM) is a highly topical issue. In this work, we discussed the effect of short virgin/reclaimed carbon fibers and magnetite on the electrodynamic properties of acrylonitrile butadiene styrene (ABS) in the X-band frequencies. The choice of selected frequency range is connected with a large number of various radio engineering systems operating with these frequencies, including radar and satellite communication systems. Composites with the addition of short carbon fiber and magnetite exhibit excellent shielding factors ranging from 37.9 to 33.7 dB at frequencies 8–12 GHz. A detailed study of the electrodynamic parameters revealed the attractive properties of reclaimed carbon fiber as a component of shielding materials, especially with the simultaneous addition of magnetite. It should be noted that for this particular composite, the permittivity imaginary part increase was up to −23.96 (88 %) at 8 GHz compared to the virgin carbon fiber and magnetite composite.