The Material Girl launched a legal battle to adopt Mercy in April, but her bid was rejected on the grounds that prospective parents have to be resident in the country for 18 to 24 months prior to an adoption.
But the star was given the green light by judges on Friday to legally adopt the 4-year-old after the rejection was overturned.
Chief Justice Lovemore Munlo told the court that the star's commitment to the children of Malawi should be recognized after announcing his decision.
Madonna adopted Malawian-born David Banda in 2006, amid criticisms that she side-stepped the country's adoption laws. The star also has two biological children: Lourdes, 12, and Rocco, 8.
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