The authors demonstrate the continuous tuning of the electronic structure of atomically thin MoS₂ by applying uniaxial tensile strain to flexible substrates. They observe a redshift in the direct gap transitions at a rate of approximately 70 meV per percent applied strain, and a larger rate of 1.6 times higher for indirect gap transitions. These findings are consistent with first principles calculations and suggest that strain can be used to tune the electronic and optical properties of 2D crystals, which have potential applications in flexible electronics and optoelectronics. The study uses a cantilever device to apply strain and measures the strain dependence of the electronic structure through absorption and photoluminescence spectroscopy. The results show that the strain effect is independent of the crystallographic orientation within the range of 0.5% strain applied. This work opens up new opportunities for mechanically engineering the electronic and optical properties of 2D materials.The authors demonstrate the continuous tuning of the electronic structure of atomically thin MoS₂ by applying uniaxial tensile strain to flexible substrates. They observe a redshift in the direct gap transitions at a rate of approximately 70 meV per percent applied strain, and a larger rate of 1.6 times higher for indirect gap transitions. These findings are consistent with first principles calculations and suggest that strain can be used to tune the electronic and optical properties of 2D crystals, which have potential applications in flexible electronics and optoelectronics. The study uses a cantilever device to apply strain and measures the strain dependence of the electronic structure through absorption and photoluminescence spectroscopy. The results show that the strain effect is independent of the crystallographic orientation within the range of 0.5% strain applied. This work opens up new opportunities for mechanically engineering the electronic and optical properties of 2D materials.