AbstractPotassium (K)‐based batteries are viewed as the most promising alternatives to lithium‐based batteries, owing to their abundant potassium resource, lower redox potentials (−2.97 V vs. SHE), and low cost. Recently, significant achievements on electrode materials have boosted the development of potassium‐based batteries. However, the poor interfacial compatibility between electrode and electrolyte hinders their practical. Hence, rational design of electrolyte/electrode interface by electrolytes is the key to develop K‐based batteries. In this review, the principles for formulating organic electrolytes are comprehensively summarized. Then, recent progress of various liquid organic and solid‐state K+electrolytes for potassium‐ion batteries and beyond are discussed. Finally, we offer the current challenges that need to be addressed for advanced K‐based batteries.