“It’s a beautiful and positive judgement,” lawyer Alan Chinula told reporters outside the courthouse in the capital Lilongwe.
“Finally the court has granted Madonna full adoption rights of the boy ... It’s all over, thank God.”
Madonna and husband Guy Ritchie were not present for the judgement which had been expected following a recommendation to the court by a social worker who visited the couple at their London home with the boy, David Banda.
A court had initially granted an interim custody order 18 months ago.
The social worker, Simon Chisare, was present for yesterday’s hearing but refused to talk to reporters.
David’s father, Yohane, had given his backing to the adoption so his son can escape a life of grinding poverty.
Having given birth to a daughter, Lourdes, and a son, Rocco, Madonna was won over by tiny David on a visit to an AIDS orphanage in October 2006.
Although Madonna herself has been widely praised for her charity work in Malawi, the adoption case triggered a storm of controversy in the southeast African nation.
A coalition of 67 local rights groups challenged the interim custody order on the grounds that existing laws in Malawi do not allow for international adoptions.
Chinula said he hoped the “well-researched judgement” would help bring clarity in similar cases in the future.
“This judgement will have a lot of positive impact on future adoptions,” he said.