We present a novel lab-on-a-tube technology, which is a combination of three-dimensional (3D) cylindrical photolithography and nanoimprint processes, for fabricating microfunctional structures on a tiny tube substrate directly. As an example, electrochemical electrodes, which consisted of Pt work and Ag/AgCl reference electrodes, were successfully fabricated on a 330-μm-diameter polyimide capillary. Using thermal nanoimprint technology, a microdome array with a diameter of 2 μm to about 600 nm was prepared in the work and reference electrodes. The nanoimprinted domes greatly enhanced the electrochemical activity and there were much higher oxidation and reduction current peaks observed in cyclic voltammetry curves of the nanoimprinted electrode than those of the blank electrode without the nanoimprint modification. The nanoimprinted patterns exhibited complicated effects, e.g. the 600-nm-diameter dome sample has higher electrochemical activity than the 2-μm-diameter dome, while the latter has a larger surface. By using the new lab-on-a-tube technology, new bio- and nanomaterials could be integrated directly into electronic devices on tiny tube substrates so that many interesting applications could be expected in medical and life technologies.