Alexander, a pupil at The Leys School in Cambridge, has been placed first in the Intermediate category of this year's Bebras Computing Competition, ahead of more than 185,000 participants from all over the world.
In addition, four other pupils from the school were placed in the Top 500 in their respective categories and two pupils in the Top 1000.
The Bebras Computing Competition is held annually and aims to introduce computational thinking to students.
It is organised in more than 50 countries and completed online in the participants' schools.
Tom Fung, Head of IT at The Leys, said: "I am immensely proud of all our pupils for how well they have performed in this year's competition.
"It has been wonderful to see this year's results and Alex's achievement in ranking first ahead of so many participants really must be celebrated.
"I wish all the pupils well as they head to the next invite-only competition, the Oxford University Computing Challenge, which takes place in January."
Alex was awarded a Raspberry Pi computer by the school to recognise his achievement.