Chambers, systems, and methods for electrochemically processing microfeature workpieces are disclosed herein. In one embodiment, an electrochemical deposition chamber includes a processing unit having a first flow system configured to convey a flow of a first processing fluid to a microfeature workpiece. The chamber further includes an electrode unit having a plurality of electrodes and a second flow system configured to convey a flow of a second processing fluid at least proximate to the electrodes. The chamber further includes a barrier between the processing unit and the electrode unit to separate the first and second processing fluids. The barrier can be a porous, permeable barrier or a nonporous, semipermeable barrier.