The flamboyant star, who died in 1991, landed the top spot in the poll, carried out by Internet market research website OnePoll.com.
Mercury, who beat Elvis Presley to claim the title, sold 300 million records after forming Queen in 1970.
He was renowned for his charismatic stage presence during his 21 years with the band.
David Bowie, 63, was third in the poll.
Next up was Bon Jovi frontman Jon Bon Jovi, 48, followed by Jimi Hendrix, Kurt Cobain, Jim Morrison, Slash, 45, and Bono, 50.
'Freddie Mercury had it all the voice, the image, the stage presence, everything,' the Daily Star quoted OnePoll.com spokesman as saying.
'He was idolised around the world by millions of fans and his legend will live on forever.
'He combined his ear for music with an ability to deliver to stadium audiences and millions were devastated when HIV finally killed him in 1991,' he added.
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