We review the recent progress in thermal characterization and sensor applications of one-dimensional nanostructures employing microelectromechanical system (MEMS) devices. It was found by thermal measurements that the thermal conductance of a single wall carbon nanotube (SWCNT) was very close to the ballistic thermal conductance of a 1-nm-diameter SWCNT without signatures of phonon-phonon Umklapp scattering, a high thermoelectric figure of merit can potentially be obtained in bismuth telluride (BixTe1-x) nanowires with an optimized atomic ratio of x, and the thermal conductivity of metal oxide nanobelts was suppressed by increased phonon-boundary scattering. We further suggest that dielectrophoresis and other directed-assembly methods can be used for the large-scale integration of nanowires with MEMS to obtain ultrasensitive, stable, and selective sensor systems.