Abstract <p>We present the first experimental report of the complete elastic tensor of incipient ferroelectric KTaO₃ between 9.6 and 307 K, using resonant ultrasound spectroscopy (RUS). The elastic constants C₁₁ and C₄₄, as well as the bulk and shear moduli increase roughly linearly upon cooling. Deviations from such dependence are a result of impurities. Zener anisotropy factor is 0.697 at room temperature and decreases to 0.627 at 9.6 K, indicating increasing elastic anisotropy. The temperature dependence of C₁₂ is anomalous with no stiffening on cooling, which could be a result of different defect species influencing C₁₂ but not the other constants, possibly due to defect anisotropy. The values of elastic constants and anisotropy are compared at room temperature and below 10 K with the literature reporting experimental results and density functional theory calculations.</p>