The country’s Vice-President Nangolo Mbumba declared the news in the early hours of Sunday morning.
The news comes less than three weeks after it was revealed that the President had been diagnosed with cancer.
"At his side was his dear wife Madame Monica Geingos and his children," Mr. Mbumba stated in a released statement.
"The Namibian nation has lost a distinguished servant of the people, a liberation struggle icon, the chief architect of our constitution, and the pillar of the Namibian house."
President Geingob passed away at Lady Pohamba Hospital in the capital, Windhoek, with his family by his side. The announcement of his death urged the nation to remain calm while the government takes care of the necessary state arrangements, preparations, and other protocols.
The late leader had publicly disclosed his cancer diagnosis just last month after undergoing a routine colonoscopy and gastroscopy.
Though details about the specific type of cancer and prognosis were not disclosed, it was mentioned that he would continue to fulfill his presidential duties during his treatment.
President Geingob had traveled to the United States for medical care and was expected to return to Namibia on February 2.
His health struggles were not new, as he had undergone brain surgery in 2013 and survived prostate cancer the following year.
In 2023, he also announced that he had undergone aortic surgery in neighboring South Africa.
The nation is urged to remain composed during this period of deep sorrow, with further announcements regarding state arrangements and protocols to follow, according to Acting President Mbumba.
Namibia, which gained independence from South Africa in 1990, is scheduled to hold presidential and parliamentary elections in November.
Geingob, ineligible for reelection due to constitutional limits on presidential terms, leaves the ruling SWAPO Party's presidential candidacy to Nandi-Ndaitwah.
If elected, she would become the country's first female head of state. The political landscape of Namibia faces an uncertain future as the nation mourns the loss of a pivotal leader.