Her parents, Luyanda and Prudence Jezile, hail from East London in the Eastern Cape and have been living in the United Kingdom for more than 10 years.
The 11-year-old, Asanda Jezile, is one of 12 singers who made it to the finals of Simon Cowell's show and could walk away with R3.8m in prize money on Saturday.
'Child of the African soil'
The Dispatch Online said locals had posted messages of support on social networking site Facebook.
Sibongile Ngobese wrote: "Hey Luyanda, I saw Asanda on YouTube. I am so proud of her and wishing her all the best. Pity we cannot vote from South Africa. To all South Africans in UK, please support Asanda by voting."
Margie Hoole wrote: "And proudly South African I remain. Asanda, show them what we are made of."
Buti Chuma wrote: "You making us very proud in South Africa. You are a girl child of the African soil."
Watch Asanda perform Rihanna's Diamonds on Britain's Got Talent: