The functionalized utilization of lignin is attracting more and more attention. In this paper, we report a 3D interconnected foamy carbon material with highly open pore structure. The carbon foam is synthesized by depolymerization reforming strategy. The foamy carbon has a deep internal pore channels and exhibits an enhanced electrosorption capacity. The highest desalination of the foamy carbon reaches 30.2 mg·g−1 in 500 mg·L−1 NaCl at 1.2 V with adsorption rate of 3.75 mg/g/min. Meanwhile, the optimal electrode PDLC-1 shows good regeneration capacity. Our work provides a usable way for the preparation of lignin-derived carbon foam with high-performance of capacitive deionization. •Depolymerization-reforming lignin regulates its agglomeration behavior.•An efficient strategy to prepare carbon foam with highly open porous structures.•The ultra-high electrosorption performance and cycle stability are observed.