After actively exploring in recent years, flow-electrode capacitive deionization (FCDI) demonstrates potential for commercial application as an electrically driven ion removal method characterized by easily scalable structures, continuous operation, and flexibility in resource recovery. This overview discusses the current progress in scaling up and optimizing designs for this promising technology. Common performance metrics for FCDI are standardized to ensure fair evaluation and comparison of different desalination systems. Based on practical applications, this review focuses on comparing material and design optimization. We summarize relevant environmental applications, such as the selective removal of charged pollutants and selective resource recovery, to illustrate selectivity. Lastly, we highlight the most pressing challenges facing FCDI industrial applications and discuss future research directions, considering the advantages and disadvantages of various FCDI approach designs.