Miniaturized light sources at telecommunication wavelengths are essential components for on-chip optical communication systems. Here, we report the growth and fabrication of highly uniform p-i-n core-shell InGaAs/InP single quantum well (QW) nanowire array light emitting diodes (LEDs) with multi-wavelength and high-speed operations. Two-dimensional cathodoluminescence mapping reveals that axial and radial QWs in the nanowire structure contribute to strong emission at the wavelength of ~1.35 and ~1.55 μm, respectively, ideal for low-loss optical communications. As a result of simultaneous contributions from both axial and radial QWs, broadband electroluminescence emission with a linewidth of 286 nm is achieved with a peak power of ~17 μW. A large spectral blueshift is observed with the increase of applied bias, which is ascribed to the band-filling effect based on device simulation, and enables voltage tunable multi-wavelength operation at the telecommunication wavelength range. Multi-wavelength operation is also achieved by fabricating nanowire array LEDs with different pitch sizes on the same substrate, leading to QW formation with different emission wavelengths. Furthermore, high-speed GHz-level modulation and small pixel size LED are demonstrated, showing the promise for ultrafast operation and ultracompact integration. The voltage and pitch size controlled multi-wavelength high-speed nanowire array LED presents a compact and efficient scheme for developing high-performance nanoscale light sources for future optical communication applications.