Liquid photonic crystal (LPC) is a promising new material in the field of sensing, display, printing, and coating due to its unique fluidity, metastability, and reversibility in colloidal assembly. However, it is a big challenge to prepare LPC materials in an efficient, controllable, and eco-friendly way. In this work, an electrically-driven colloid concentration process was developed for the efficient synthesis of LPC. The key for the synthesis was that the electrophoretic process produced a locally concentrated but “agglomeration-free” colloidal solution, which spontaneously turned to LPC after being kept standing for a few minutes. The synthesis possessed good universality and reproducibility for LPCs composed of different particles and solvents. Its efficiency could be improved by tuning the particles’ surface charge, the dielectric constant and viscosity of the solvent, as well as the external field conditions. More importantly, it could be developed into a large-scale and green process without chemical wastes compared to the previous synthetic methods.