We present a comprehensive analysis of structural and charge transport properties of high-quality N-polar InN/In0.57Al0.43N heterostructures grown by metalorganic chemical vapour deposition (MOCVD) on on-axis c-plane sapphire substrate and off-axis c-plane sapphire substrate misoriented by 4° toward the a-plane. Instead of a typical GaN template, we included an In-rich InAlN buffer layer to mitigate the lattice mismatch between InN and sapphire. We observed a strong correlation between the structural quality of InN and the electron mobility that was measured in a broad temperature range. Experimental results showed that InN grown at 550 °C had a higher density of edge-type dislocations, weaker temperature dependence of electron mobility, and higher electron concentration compared with InN grown at 600 °C. Our results suggest that acoustic phonon piezoelectric scattering dominated between 150 and 300 K, while dislocations and interface scattering prevailed from 10 to 150 K. The highest electron mobility of 714 cm2/Vs at room temperature was obtained for InN grown at 600 °C on the on-axis substrate, which corresponded with the lowest density of edge-type dislocations (2.7 ✕ 1010 cm−2) and the best surface morphology with a root-mean-square roughness of 1.4 nm.