Laurent Simons, whose father is Belgian and mother Dutch, and has an IQ of 145 according to his parents, collected a diploma with a class of 18-year-olds.
Speaking to Belgium’s RTBF radio, Laurent said his favourite subject was maths “because it’s so vast, there’s statistics, geometry, algebra”.
After a two-month holiday from school, he will start university.
His father said his son had struggled when he was younger to play with other children, and had not been particularly interested in toys.
Laurent said he had considered becoming a surgeon and an astronaut but was now thinking about going into computers.
“If he decided tomorrow to become a carpenter, that would not be a problem for us, as long as he is happy,” his father said.