Composites of carbon fibers (CFs) and magnetic metals have concerned attention for tunable microwave absorption materials (MAMs). In this work, magnetic nickel (Ni) particles were coated on the CFs surface by an electroplating technique. Some important parameters for nickel deposition of the CFs surface were analyzed and optimized. The influence of current density, temperature, and time on the weight gain and electrical conductivity of nickel-coated CFs has been investigated. The temperature of the electroplating bath has no significant effects on the weight gain, and the applied current density and time only control the weight of the samples. The special effects of the current density and time are higher than that of temperature on the electrical conductivity. As for surface morphology results, the smooth and micro-cone shapes were formed with lower and higher values of electroplating parameters, respectively. The optimization results showed that the most optimal weight gain and electrical conductivity were to be 38 wt% and 585 S/cm, respectively, and achieved at the electrical current density of 2.5 A/dm2, the electroplating temperature of 25 °C and time of 20 min. The shielding efficiency (SE) of optimized nickel-coated CFs increased up to -63.71 dB. Moreover, different morphology of Ni-coated CFs was established by setting the plating time. The microstructure, electric and magnetic properties, complex permittivity and permeability, and reflection loss (RL) of the Ni-coated CFs were specified as a function of the surface morphology of composites. The creation of a magnetic Ni layer onto CFs improved composite properties, not only raising the saturation magnetization (17?46 emu/g) but also enhancing electrical conductivity (361?594 S/cm). The minimum RL could reach up to ?64.8 dB at 14.9 GHz with 2.0 mm matching thickness and high effective bandwidth of 2.2-18.0 GHz. It has been displayed that the properties of Ni-coated CFs can be effectively controlled by changing the morphology of the Ni layer, which provides a novel route to fabricate Ni-coated CFs with tunable and broadband microwave absorption properties.