Pulsed metal organic chemical vapor deposition was employed to grow nearly polarization matched InAlGaN/GaN heterostructures. A relatively low sheet carrier density of 1.8×1012 cm?2, together with a high electron mobility of 1229.5 cm2/V·s, was obtained for the prepared heterostructures. The surface morphology of the heterostructures was also significantly improved, i.e., with a root mean square roughness of 0.29 nm in a 2 μm×2 μm scan area. In addition to the improved properties, the enhancement-mode metal–oxide–semiconductor high electron mobility transistors (MOS-HEMTs) processed on the heterostructures not only exhibited a high threshold voltage (VTH) of 3.1 V, but also demonstrated a significantly enhanced drain output current density of 669 mA/mm. These values probably represent the largest values obtained from the InAlGaN based enhancement-mode devices to the best of our knowledge. This study strongly indicates that the InAlGaN/GaN heterostructures grown by pulsed metal organic chemical vapor deposition could be promising for the applications of novel nitride-based electronic devices.