The singer was initially turned down in April as she'd not been a resident of the African country for 18 months.
But the Supreme Court Of Appeal has overturned the ruling.
Madonna, 50, is now expected to move Mercy to her New York home.
She has daughter Lourdes, 12, with her ex Carlos Leon, and sons Rocco, 8, and adopted David Banda, 3, with ex-husband Guy Ritchie, 40.
Where next?- A guide to adoption
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