A positive active material for a rechargeable lithium battery including a lithium metal compound and a phosphorus (P)-containing compound on the surface of the lithium metal compound. A content of phosphorus (P) of the phosphorus-containing compound is about 0.1 atom % to about 10 atom % based on the total amount of elements on the surface of the positive active material. A method of preparing the same and rechargeable lithium battery including the same are also provided.