‘All I Want for Christmas Is You’ co-writer slams Mariah Carey

Mariah Carey has previously hyped that she wrote her hit “All I Want for Christmas Is You” on her Casio keyboard as a child — but her former co-producer and co-writer claims otherwise.

In fact, he’s boldly claimed she just “doesn’t understand music.”

Walter Afanasieff dropped the holiday bombshell during the “Hot Takes & Deep Dives” podcast, in which he revealed how he and Carey, 52, co-created the song shortly after collaborating on her 1993 album “Music Box.”

Afanasieff, 64, said the two of them were originally on the same page about the song — but about 10 years ago, there was suddenly an “alternate story” being told.

“When she started to hint at the fact that, ‘Oh, I wrote that song when I was a little girl!’ But why weren’t you saying that for 12 or 13 or 15 years prior to that? So it just sort of developed in her mind,” he said.

Carey told Billboard in 2017 that she came up with the song when she was just a kid.

“I am proud of this song that I wrote basically as a kid on my little Casio keyboard,” she said at the time.

However, Afanasieff has now come forward to boldly claim that the chart-topping, Grammy-winning singer-songwriter is actually musically challenged.

“She doesn’t play anything, she doesn’t play keyboard or piano. She doesn’t understand music, she doesn’t know chord changes and music theory or anything like that. She doesn’t know a diminished chord from a minor seventh chord to a major seventh chord,” Afanasieff claimed.

The Post has reached out to Carey’s reps for comment about Afanasieff’s accusations.

“So to claim that she wrote a very complicated chord-structured song with her finger on a Casio keyboard when she was a little girl, it’s kind of a tall tale,” he added on the podcast. “I’ve studied music, I have degrees in music. I’m an accomplished orchestrator and arranger. I teach music. I’m not a schlump. I don’t play by ear.”

Afanasieff said he and Carey came up with the song together while working on three songs for her Christmas album, “Merry Christmas.”

“We were holed up in this beautiful home that they were renting, and it was the summertime and there was a piano. So the writing of ‘All I Want for Christmas’ is, I started playing a boogie-woogie, kind of a rock,” he said while making the sound of the baseline.

The producer charged that he was playing the piano when Carey starting singing, “I don’t want a lot for Christmas.”

“So on and on, and it was like a game of pingpong. I’d hit the ball to her, she hits it back to me,” he said.

Afanasieff said the singer was responsible for the melodies and lyrics while he took charge of the music and chords.

However, Carey told a different version of the events in her documentary “Mariah Carey is Christmas: The Story of ‘All I Want for Christmas is You.’”

She implied that she started the song on her own before “getting in the studio” with Afanasieff.

Both Afanasieff and Carey are equally credited for the hit Christmas song, with no other writers or producers.

They worked together on a number of her studio albums, including “Emotions” and “Music Box.”

This isn’t the first pushback the singer has gotten for her hit song.

Andy Stone, who co-wrote Vince Vance & the Valiants’ country song “All I Want for Christmas Is You,” filed a $20 million lawsuit against both Carey and Afanasieff for copyright infringement, claiming they never sought or obtained use of the title.

Meanwhile, Carey’s “All I Want for Christmas Is You” was released in 1994 and continues to make its way to the top of the charts every holiday season.