The pop star was greeted at the Kondanani children's village near Malawai's commercial capital by a crowd of about 28 singing orphans who each received a translated copy of her book "English Rose."
Bodyguards prevented reporters from getting access to the premises or approaching her. Orphanage officials said her husband, director Guy Ritchie, accompanied her and filmed the brief visit.
"She and her husband are very lovely," said orphanage director Anne Chikhwaza. "She has a kind heart. She really wants to help."
She said Madonna didn't make any financial pledges "but appreciates the work we are doing here."
Madonna's publicist, Liz Rosenberg, said Thursday that the star was on a private trip working on projects for children and dismissed statements from Malawian government officials that she would adopt a boy.
"Madonna has not adopted a baby boy as has been previously and incorrectly reported," Rosenberg said in an e-mail to The Associated Press in Los Angeles. "She is on a private visit to Malawi and is involved in the building of an orphanage/child care center as well as other initiatives to help the children of that country who have lost parents to AIDS."
"I have no information or confirmation regarding Madonna adopting an individual child. She's kind of adopting an entire country of children."
Malawi is among the poorest countries in the world, trapped in a seemingly endless cycle of hunger and disease. More than 14 percent of Malawi's 12 million people have HIV, the virus that causes AIDS, and an estimated 1 million children have been orphaned.
Madonna's project, called Raising Malawi, aims to set up an orphan care center to provide food, education and shelter for up to 4,000 children. It will have projects based on Kabbalah, Jewish mysticism that has gained popularity in recent years and which counts the 48-year-old singer among its devotees.
The care center is based in Mphandula, a village about 30 miles from Lilongwe, the capital.
There had been reports that Madonna would visit Mphandula, as well as two orphanages in the commercial capital, Blantyre. However, there was no sign of the star and organizers refused to give details of her itinerary.
Philippe van den Bossche, project coordinator for Raising Malawi, said only that he welcomed the visit to the southern African state by the center's patron.
"Any organization would be happy to know that they are being supported by such a beacon of hope. We are very grateful for the work she is doing in the country and for the project," he said. "She is an extraordinary inspiration and will hopefully inspire people to put children first."
Van Den Bossche said the orphan care center would be completed next March, a year after work on it began.
In villages such as Mphandula, many orphans are cared for either by siblings or grandparents who struggle to find food for the extended family. The village has no electricity and the inhabitants live in mud and thatched huts.
In a letter on the organization's Web site, Madonna said she hoped to help "bring an end to the extreme poverty and degradation suffered by Malawi's orphans."
Madonna joins a growing list of entertainer-activists who have focused on Africa.
Angelina Jolie and Brad Pitt, whose child was born in Namibia earlier this year, recently announced they would donate $1 million each to two humanitarian organizations active on the continent. They also have two adopted children — one from Ethiopia and one from Cambodia.
Andrina Mchiela, a senior official with Malawi's Ministry for Gender and Child Welfare, told the AP on Wednesday that if they adopt, Madonna and her husband would be subject to a probation period required of all prospective adoptive parents.
"After her husband and her fill in the papers, we'll allow them to take him away, not as adoptive parents but foster parents until after the 18 to 24 months, when the government of Malawi will assess whether they are a suitable family," she said. "This is a legal requirement that cannot be fast-tracked."
Madonna and Ritchie have a son, Rocco, 5. The singer also has a daughter, Lourdes, 9.