The singer, who was raised as a Jehovah's Witness, converted to Islam in a ceremony at a friend's house in Los Angeles.
He is said to have sat on the floor and worn a small hat while an imam officiated.
According to The Sun, the ceremony took place while Jackson, 50, was recording an album at the home of Steve Porcaro, a keyboard player who composed music on his Thriller album.
The former Jackson 5 star was counselled by David Wharnsby, a Canadian songwriter, and Phillip Bubal, a producer, who have both converted.
A source said Jackson had appeared a "bit down" and added: "They began talking to him about their beliefs, and how they thought they had become better people after they converted. Michael soon began warming to the idea.
"An imam was summoned from the mosque and Michael went through the shahada, which is the Muslim declaration of belief."
Last year his brother, Jermaine Friday, suggested Jackson would convert having taken an interest in Islam since Friday's conversion in 1989.
"When I came back from Mecca I got him a lot of books and he asked me lots of things about my religion and I told him that it's peaceful and beautiful," said Friday.
"He read everything and he was proud of me that I found something that would give me inner strength and peace.
"I think it is most probable that Michael will convert to Islam.
"He could do so much, just like I am trying to do. Michael and I and the word of God, we could do so much