Hayley Abdullah, an A-level pupil who joined the elite club when she was just 10, was picked for the Mensa board in an election by 2,500 of society's members.
Hayley, from Peterborough, Cambridgeshire, has applied to Cambridge University to study law and counts learning Chinese among her hobbies.
She said: "I felt that there needed to be more things done for junior members of Mensa, and that I had an ideal opportunity to ensure they were fairly represented.
"I hope for Mensa to grow bigger and better, and to develop a stronger image with a lot less stereotyping."
Only 2 per cent of applicants satisfy Mensa's requirement of a minimum IQ of 148.
One of Hayley's first duties when the board meets later this month will be to elect a new chairman to replace Sir Clive Sinclair