The Oscar-winning composer revealed that he wanted to counter the conspiracy theories regarding an apocalypse on December 21 with a message of hope.
Speaking to The Hindustan Times, he said: "After about 15 years, I finally got the chance to spend time on a personal project. There have been predictions that the world will come to an end on 21.12.12. But I look around me and I see so much scope for hope, joy and, most importantly, love."
It will be the first solo single for Rahman since 1997. The world-renowned composer is reportedly collaborating with some of the biggest names in Hollywood for the song.
The composer, who staged a peace concert in Australia in 2009, said the theme of the song was love.
"Mankind has the innate capability to love, and that is what this single is about - a rainbow of hope. When we are all tuned with positive thoughts, we can change disastrous destinies," he added.
Rahman most recently composed a song for the London 2012 Olympics Opening Ceremony .
His song will be released next week by Sony Music.