Data shared here is new K isotopic compositions of high-Mg andesites used in the article "Potassium isotopic evidence for recycling of surface water into the mantle transition zone" by Kai-Chen Xing, Feng Wang, Fang-Zhen Teng, Wen-Liang Xu, Yi-Ni Wang, De-Bin Yang, Hong-Lin Li, and Yan-Chao Wang published in Nature Geoscience