SignificanceNitric oxide (NO) plays key roles in coordinating plant growth and development with environmental cues. Potassium (K+) is an essential plant nutrient important for growth and stress tolerance. However, little is known about the molecular connection of NO to K+homeostasis. Through a genetic approach, this study provides a detailed regulatory mechanism of NO to K+channel AKT1-mediated K+absorption, through its modulation on vitamin B6 biosynthesis in plants. This finding demonstrates a previously unidentified role of NO in the control of K+content in plants, which may represent a normal plant adaptive response under unfavorable external conditions.