Efficient electromagnetic interference (EMI) shielding is central to modern electronics. Current EMI shielding strategies use metals with high cost, poor flexibility, and difficult processability to reflect/absorb incoming electromagnetic waves. Advanced materials and solution processing techniques for EMI shielding are therefore of vital interest to industry and academia for large-scale manufacturing. Here, the state-of-the-art of solution-processed nanocomposites is reviewed for EMI shielding, examining the topic from both the materials, and the colloidal dispersion engineering perspectives. The physics underpinning EMI shielding is explored by correlating the wave-matter interactions between electromagnetic waves and shielding materials. Various designs of the nanocomposites are explored to overcome trade-offs in shielding effectiveness and solution-processability. An overview of the types of fillers and preparation methods for the polymer nanocomposites is provided, with special emphasis placed on material designs and engineering approaches to produce nanocomposites with outstanding shielding performance and excellent properties. Shielding effectiveness, measured in decibels (dB), is the key performance metric to guide the development of EMI shielding materials. Various solution-processable fabrication techniques, including casting, coating, and printing, are discussed in correlation with the dispersion formulations and the operating principles. Recent advances in solution-processable nanocomposites for EMI shielding are presented with their current limitations and future prospect analyzed.