Metal-organic framework (MOFs)-derived magnetic metal/carbon composites have shown tremendous potential for lightweight microwave absorption materials. Flaky Co/C composites were synthesized by pyrolysis process using two-dimensional flaky Co/Zn bimetallic MOFs as precursors. The effects of Co/Zn molar ratios in the precursor on the morphology structure, graphitization degree, magnetic properties and microwave absorption properties of the composites were investigated. As a result, Co nanoparticles are uniformly distributed in the carbon framework, As the Co content decreases, the graphitization degree of carbon components in composites is decreased, and the magnetic properties are weakened. The microwave absorption properties of flaky Co/C composites are first enhanced and then weakened with the decrease of Co content. The composite with the filling ratio of 30 wt% and Co/Zn molar ratio of 4:1 shows the best microwave absorption properties. The minimum reflection loss (RL) of ?23.09 dB is achieved at 10.8 GHz with the thickness of 2.11 mm. The maximum effective bandwidth (RL≤?10 dB) reaches 4.96 GHz with the thickness of 1.62 mm. The excellent microwave absorption performance of composites mainly due to the synergistic effects of uniformly distributed magnetic Co nanoparticles and carbon frameworks, which enhanced the conduction loss and interfacial polarization and improved the impedance matching.