Early diagnosis and therapy of cancer metastasis are of great importance for disease outcome. Circulating tumor cells (CTCs) offer the ability for noninvasive tumor profiling in real time. However, simply capturing and counting tumor cells are inadequate to provide valuable information about tumor. Efficiently releasing the captured cells is necessary for the downstream characterization. Herein, we describe a mild electrochemical strategy to effectively isolate CTCs from the bloodstream and rapidly release the captured cells in 2 min for downstream molecular characterization, as realized on a conductive poly(aminophenylboronic acid) derivatized electrode. The boronic ester linkage between dopamine (DA) and boronic acids-functionalized electrode is stable, and only upon the application of a weak potential perturbation does the boronic ester dissociate and release cells without compromising cell viability. This platform is reusable after acid treatment and has the potential to be the next-generation platform for cell capture and release, realizing the clinical value of CTCs as biomarkers.