The artist described the new arrival as "the most amazing thing ever on this planet" after giving birth earlier this week.
Her son was due on February 8, placing the 31-year-old's planned Grammy Awards performance in doubt. However, she collaborated with T.I., Kanye West, Jay-Z and Lil Wayne as she sung her hit 'Paper Planes' at the ceremony.
The London-born Sri Lankan singer gave birth to a boy three days later in LA, reports People. She wrote on her MySpace blog: "My baby was born Wednesday, he is healthy, fine, beautiful and the most amazing thing ever on this planet, of course, I'm his mum!"
M.I.A announced that she and her fiancé Benjamin Brewer, lead singer and guitarist of The Exit, were expecting their first child.
The new mum is expected to perform at the Academy Awards ceremony on February 22, where 'O Saya' from Slumdog Millionaire is running for best song.