AbstractThe so‐called address‐flow principle is described: a valveless, electroosmotically driven technology used for controlling the stream profile in a laminar flow chamber. The method is explained, and a theoretical description and experimental verification are presented. Adjustment of the flow of two electroosmotically controlled guiding streams, running parallel to a central sample stream, can be used for positioning the sample stream in the dimension perpendicular to the flow direction. The results presented show that address‐flow microfluidics allow easy and accurate control of sample stream position and width. The electroosmotic flow (EOF)‐controlled guiding of microfluidic flows described in this paper, is a new unit operation that might aid in separation and collection in microfluidic devices. One possible application of address‐flow microfluidics is guiding of capillary electrophoresis‐separated components over a multisensor array, in order to perform affinity assays.