In this work, the development of a packed immobilized enzyme reactor (IMER) and its integration to a capillary electrophoresis microchip is described. The present microchip design differs from others, in the fact that the same design could be used with or without the particles and, just by changing the material used to pack the IMER, different analytes can be detected. The applied procedure involves the separation of the target analyte by capillary electrophoresis (CE), which is then coupled to a post-column IMER that produces H2O2. The H2O2 produced is finally detected downstream at the surface of a working electrode. Glucose was detected above 100 μM by packing particles modified with glucose oxidase at the end of the separation channel. The analytical performance of the microchip-CE has been demonstrated by performing the separation and detection of glucose and noradrenaline. Additions of fructose showed no effect on either the peak position or the peak magnitude of glucose. The microchip-CE-IMER was also used to quantify glucose in carbonated beverages with good agreement with other reports.