Debate has raged for decades since the song's release in the '70s about who the egotistical subject of her signature track actually is. Suspects have included her former lovers Mick Jagger, Kris Kristofferson, Cat Stevens and Warren Beatty.
However, the 64-year-old has now claimed that the track is actually about openly gay record label boss David Geffen, the Daily Mail reports.
Simon admitted that she ended the 38-year mystery by whispering Geffen's name backwards on a reworked version of the song for her forthcoming record Never Been Gone.
She had previously maintained that the character in the song was a 'composite' of people she knew.
Geffen was head of her Elektra record label in 1972, when she originally wrote the track. It is believed that the source of Simon's ire was Geffen repeatedly choosing to promote her rival Joni Mitchell over her.