The 128-acre spread on the Salmon River near Stanley, which includes a 7,300-square-foot lodge, had been priced at $19 million in 2006.
Besides the lodge, there also is a private owner's residence, a caretaker's home, a recording studio and eight historic log cabins.
"This is huge for a national forest holding," Stoney Burke, the listing agent with Hall and Hall Ranch Brokers, told the Idaho Mountain Express.
The ranch has been King's primary residence for 29 years but Burke said she wants to sell it so she can spend more time with family in Los Angeles, the newspaper reported Sunday.
King also has a condominium in Ketchum, where she is to perform with longtime friend James Taylor July 12, and homes in California and New York.