Mugabe along with his wife arrived on Thursday in an open-top vehicle at the stadium.
They waved their fists at the crowd before the national anthem was played.
Several African leaders are also attending the ceremony boycotted by Mugabe’s rival Morgan Tsvangirai. About 40 heads of state and government are reportedly attending President Mugabe’s inauguration.
A court appeal filed by Tsvangirai over fraud allegations in the July 31 election had delayed the ceremony. Mugabe won the race with 61percent of the votes to serve as president for the seventh consecutive term in office.
On August 9, Tsvangirai’s Movement for Democratic Change (MDC) filed a legal challenge to Mugabe’s victory. MDC lawyers argued that the election must be annulled because of alleged election irregularities.
The African Union has also backed the official election result
Mugabe and Tsvangirai have been sharing power since 2009, following a deal brokered by a regional bloc to end the unrest sparked after a disputed poll in 2008.
Violence broke out in the last presidential election in 2008, forcing Tsvangirai out of the race despite a first round win after 200 of his supporters were killed in the unrest.
Mugabe, 89, has become Africa’s oldest leader, having ruled Zimbabwe since its independence in 1980.