The former South African president spent 27 years in jail for leading an often armed anti-apartheid movement and is affectionately called "Madiba".
On Wednesday, Mandela chose to spend his special day quietly with his family in his village home of Qunu in the Eastern Cape province, BBC reported.
US President Barack Obama and his wife Michelle Obama paid tribute ahead of Mandela's birthday.
The US first couple hailed Mandela's "extraordinary life and steadfast commitment to the principles of democracy and reconciliation".
On Wednesday, the South African government said: "Madiba is special to South Africa in many ways, having dedicated his entire adult life to the relentless fight for freedom, democracy, peace and stability in our country."
"As the first President of a democratic South Africa, Nelson Mandela immediately led the nation on a path of unity, transformation, forgiveness and reconciliation," reported Bua News quoting the Government Communication and Information System (GCIS).
Mandela's birthday is traditionally celebrated with the poor communities receiving help from those who are more fortunate.
After leaving prison in 1990, Mandela led the African National Congress party to a landslide victory in 1994, the first occasion the country's black majority was allowed to vote.
He stood down as South African president in 1999 having served one term, handing over to Thabo Mbeki.
Cape Town: As South Africa celebrated Nelson Mandela's 94th birthday Wednesday, about 12 million schoolchildren across the country sang a special composition - "We love you, father" - as a special greeting to the grand patriarch.
First Published: Wednesday, July 18, 2012, 19:59