It is of great significance to improve the electromagnetic wave absorption performance of absorbing materials for the application in critical fields using different techniques to design unique structure. Three-dimensional (3D) ZnO nanorods with unique microflower-like structures and high-performance microwave absorption were successfully synthesized via hydrothermal route and annealing process, which were modified by spherical-like Fe₃O₄ nanoparticles. The composites display outstanding microwave absorption property with different content of Fe₃O₄ nanoparticles and the mass ratio of ZnO/Fe₃O₄ to paraffin are 3:2. The best reflection loss (RL) value can reach -36.2 dB at 9.35 GHz with an absorber thickness of only 2.7 mm and the corresponding absorption bandwidth is 4.02 GHz (6.81-10.83 GHz) in the range of 2-18 GHz when the composites containing 11.3 wt. % Fe₃O₄ as filler. A mechanism is proposed and discussed to further understand the absorption behavior of composites. This work demonstrates a promising synthetic route to design thin, economical and wide bandwidth stable microwave absorbing materials with outstanding microwave absorption performance.