Doctors said Mandela, who was in critical but stable condition just weeks ago, is steadily improving, South African President Jacob Zuma said in a statement.
"On behalf of government and all the people of South Africa, we wish Madiba [Mandela's clan name] a joyous 95th birthday," Zuma said. "We are proud to call this international icon our own as South Africans and wish him good health."
Zuma thanked all the well-wishers for supporting Mandela "with undying love and compassion" during his hospitalization.
"We also thank all for responding to the call to give Madiba the biggest birthday celebration ever this year," Zuma said.
South Africa's first black president was rushed to the hospital June 8 for a recurring lung infection.
Mandela's birthday was also marked by Mandela Day, when schools across the South Africa honored the Nobel Peace Prize laureate and organizations asked people to volunteer 67 minutes as a tribute to his 67 years of public service, The New York Times reported.
In an interview with Britain's Sky News, one of Mandela's daughters, Zindzi Mandela-Motlhajwa, said Wednesday her father was watching television and used headphones to listen.
"You can see he is there in his eyes, the same energy and strength," she said, adding the family's birthday present to Mandela was a collage of family photographs .