Last year, Mhango competed in Egypt, finishing third and earning a candidate master rating in chess.
He told Sowetan he started playing the game when he was 10 years old.
"My aim is to be a grandmaster. Now that I'm a Fide master it means I'm recognised by the world body of chess; it bodes well for my future," said Mhango.
He said although he needed to balance his schooling with the sport, chess helped him concentrate when studying.
"Chess helps me concentrate more, that is why I find my studies easy.
"Maths and science are my easy picks because those are the subjects that demand a lot of thinking; chess keeps my mind very sharp," said Mhango.
His single mother Victoria Ngwamba said that she's over the moon about her son's achievements.
"I'm very happy, you cannot understand the joy in my heart seeing my son being respected for the sport that I don't even know," she said
She said her son was taught chess by his elder brother Senzo when he was at primary school. "Later, he came home with something he won from school. Since then he goes to countries I have never been to myself."
Ngwamba said her son's achievements have made her "very happy and proud".