Madonna, the pop star, will be allowed to adopt a second child from Malawi, the country's highest court has ruled.
Chief Justice Lovemore Munlo, sitting in Malawi's Supreme Court, said Madonna's commitment to helping other disadvantaged children in the country should have been taken into account.
Mercy has spent most of her life in an orphanage but she still has family members who are alive.
Mercy will be a sister to Madonna's two biological children Lourdes, 12, and Rocco, eight, and David Banda, the Malawian boy she took home in 2006 and whose adoption was also surrounded by controversy, particularly as his father is still alive.
In a statement released by her spokeswoman, Madonna said: "I am ecstatic... My family and I look forward to sharing our lives with her."
Rights groups claimed that Malawi's adoption rules, which require prospective parents to be resident for 18 months before the transfer can take place, were waived for the pop star because of her wealth.
Mercy's mother died soon after she was born and the girl was put into the Kondanani orphanage in Thyolo, outside Blantyre. Her father was not identified, but once the multi-millionaire pop star announced her intention to adopt her, James Kambewa, a security guard, came forward to claim that he was her parent and wanted to look after the child.
Speaking after the decision yesterday, he said: "I'm crying. I need my baby. I don't know where I can find any help."