Andrina Mchiela, a top official in the Ministry for Gender and Child Welfare, said the pop star planned to launch six projects to help underprivileged children during her stay.
She also said Madonna and her husband, director Guy Ritchie, were seeking to adopt a Malawian child.
Benston Kilimbe, director of the social welfare department, said Madonna was expected to file the adoption papers tomorrow.
“According to Malawi laws, she is expected to stay with the child for 18 months for child welfare officials to assess the suitability of the family before we finalise adoption papers,” Ms Mchiela said.
Madonna and Ritchie have a son, Rocco, five, and the singer also has a daughter, Lourdes, nine.
Madonna and an entourage landed in the capital Lilongwe with no prior announcement.
Madonna was to travel today to Mphandula, a village about 50 kilometres from the capital, where she wants to set up an education and feeding centre for children orphaned by the AIDS epidemic.
Malawi is among the poorest countries in the world, trapped in a seemingly endless cycle of hunger and disease.
HIV/AIDS infects just over 14% of the 12 million population — most of them economically active adults — and has left an estimated one million children orphaned.
In villages like Mphandula, televisions are non-existent and radios are rare, meaning that most of the villagers have never heard Madonna sing.