Rahman was born in Madras, India. His father, R. K. Shekhar, was a film-score composer and conductor for Tamil and Malayalam films; Rahman assisted his father in the studio, playing the keyboard.
After his father's death when Rahman was nine years old, the rental of his father's musical equipment provided his family's income. Raised by his mother, Kareema (born Kashturi),[ Rahman was a keyboard player and arranger for bands such as Roots (with childhood friend and percussionist Sivamani, John Anthony, Suresh Peters, JoJo and Raja) and founded the Chennai-based rock group Nemesis Avenue. He mastered the keyboard, piano, synthesizer, harmonium and guitar, and was particularly interested in the synthesizer because it was the "ideal combination of music and technology".
Rahman began his early musical training under Master Dhanraj, and at age 11 began playing in the orchestra of Malayalam composer (and close friend of his father) M. K. Arjunan. He soon began working with other composers, such as M. S. Viswanathan, Ilaiyaraaja, Ramesh Naidu and Raj-Koti, accompanied Zakir Hussain, Kunnakudi Vaidyanathan and L. Shankar on world tours and obtained a scholarship from Trinity College London to the Trinity College of Music.
Studying in Madras, Rahman graduated with a diploma in Western classical music from the school. Rahman was introduced to Qadiri tariqa when his younger sister was seriously ill in 1984. His mother was a practising Hindu. At the age of 23, he converted to Islam with other members of his family in 1989, changing his name to Allahrakka Rahman (A. R. Rahman).