Electrochemical microfluidics is a young field, but now achieving substantial successes in science, engineering, and technology. In this review article, the use of electrochemical effects for actuation in microfluidic devices is described, with a focus on electrokinetic flow. Furthermore, the use of electrochemical microfluidic devices in analytic chemistry and biochemistry is detailed, largely for separation and detection, typically exploiting electrophoretic effects. Finally, the use of electrochemical microreactors is explored, with an eye to the synthesis and processing advantages that come from microscale operations. Microfluidic devices are, more than ever, serving as a platform for nanoscience and nanotechnology, with molecular scale manipulation and detection enabled by microfluidic control of the environment.