The song is the debut single from West's forthcoming solo album and the first of several of West's surprise recordings with McCartney to be released.
"In early 2014, Paul McCartney and Kanye West first began working together in a small bungalow in Los Angeles," the record label said in a statement.
"The process that would result in 'Only One' began with a simple brainstorming session between the two: With McCartney improvising on the keyboards and Kanye vocally sketching and shaping ideas in a stream-of-consciousness riff," the label said.
"When they played back the recording afterward, something remarkable happened. Kanye sat there with his family, holding his daughter North on his lap, and listened to his vocals, singing, 'Hello, my only one...' And in that moment, not only could he not recall having sung those words, but he realized that perhaps the words had never really come from him. The process of artistic creation is one that does not involve thinking, but often channeling. And he understood in that moment that his late mother, Dr. Donda West, who was also his mentor, confidante, and best friend, had spoken through him that day."
"My mom was singing to me, and through me to my daughter," said West, whose first name Kanye means "only one."