We report the development of a multifunctional, nanostructured tungsten oxide catalytic device using block copolymer (BCP) templating, which was utilised for both the oxygen evolution reaction (OER) and epinephrine (EP) detection. The device was constructed by depositing a self-assembled BCP film atop an indium tin oxide (ITO) substrate. A tungsten precursor was then selectively coordinated into the film via liquid phase infiltration, which upon UV-ozone treatment yielded WO3 surface nanolines (NLs) with excellent surface coverage. The resulting device was firstly investigated as a photoanode for OER. The onset overpotential of the WO3NLs-ITO electrode was determined to be 240 mV and 390 mV, with and without light illumination, respectively. Moreover, the applicability of the WO3NLs-ITO device for the electrochemical sensing of EP was explored using cyclic voltammetry and amperometry, exhibiting a linear response in a wide working range of 0.5–250 μM with a sensitivity of 0.0491 μA μM−1 and detection limit of 0.086 μM. The device demonstrated high durability over multiple EP measurements, as well as strong anti-interference abilities versus well-known interfering compounds. Additionally, the device was successfully applied to accurately determine EP concentrations in commercial drug samples. The results of this study attest to the significant potential of BCP templating for developing low cost, high-performance electrocatalytic devices for future nanomanufacturing strategies.