The powerful tool of single-molecule detection and spectroscopy has so far been confined mainly to the visible spectral region. Here, we report the use of a low-cost high-power UV light emitting diode (LED) emitting at 365 nm as a light source for single-molecule detection in epi-fluorescence microscopy. The LED provides an affordable alternative to UV laser systems. The performance of the light source is demonstrated by recording fluorescence images and time-dependent fluorescence traces of single molecules of a laser dye p-bis(o-methylstyryl)benzene (bis-MSB) and of a conjugated polymer polyfluorene.