We present a design principle to develop new categories of telluride-based thermoelectric nanowire heterostructures through rational solution-phase reactions. The catalyst-free synthesis yields Te-Bi 2Te 3 "barbell" nanowire heterostructures with a narrow diameter and length distribution as well as a rough control over the density of the hexagonal Bi 2Te 3 plates on the Te nanowire bodies, which can be further converted to other telluride-based compositional-modulated nanowire heterostructures such as PbTe-Bi 2Te 3. Initial characterizations of the hot-pressed nanostructured bulk pellets of the Te-Bi 2Te 3 heterostructure show a largely enhanced Seebeck coefficient and greatly reduced thermal conductivity, which lead to an improved thermoelectric figure of merit. This approach opens up new platforms to investigate the phonon scattering and energy filtering.