The annoyed singer walked offstage after two songs at the FNB stadium in Soweto on Saturday for Mandela Sports And Culture Day.
The stadium holds up to 90,000 people and had been packed throughout the day in celebration of the life of former president Mandela.
But with the packed schedule almost finished it emptied out before Brandy made her big entrance.
While Brandy is popular in the country, her surprise performance was not revealed to the fans – who left thinking the day was over.
According to the Guardian newspaper there were no more than 40 people present.
‘Brandy performed to an empty stadium. With the stadium lights on,’ tweeted South African musician, Kabomo.
People didn’t know there was a concert after the games. No one knew Brandy was around. Maybe a 40 people audience… She sulked after two songs and walked off.’
Other Twitter users couldn’t believe their eyes.
One user, Crazy Girl Tutu, tweeted: ‘I gave up the min I saw the empty stadium. Brandy performing for the chairs!’
And another user, Dawn Ngwenya, wrote in surprise: ‘Well Brandy is going to perform for herself and Mbaks only. Stadium now empty.’
Mbaks is the South Africa’s minister of sport, Fikile Mbaks.
Brandy’s publicist could not be reached for comments.