Recent computational studies predict mechanical strain–induced changes in thermal transport, which is yet to be validated by experimental data. In this article, we present experimental evidence of an increase in thermal conductivity of nominally 200-nm-thick freestanding amorphous silicon thin films under externally applied tensile loading. Using a combination of nanomechanical testing and infrared microscopy, we show that 2.5% tensile strain can increase thermal conductivity from 1 to 2.4 W/m-K. We propose that such an increase in thermal conductivity might be due to strain-induced changes in microstructure and/or carrier density. Microstructural and optical reflectivity characterization through Raman and infrared spectroscopy are presented to investigate this hypothesis.