Lydia Sebastian, a student at the Colchester County school in Essex, England, achieved a perfect score of 162 on Mensa's Cattell III B paper, beating the scores of Einstein and Hawking by two points.
The girl was humble about being placed in the company of the noted scientists.
"I don't think I can be compared to such great intellectuals such as Albert Einstein and Stephen Hawking. They've achieved so much. I don't think it's right," Sebastian told CNN.
Mensa said Sebastian's score puts her in the top 1 percent of intelligence. The group said anyone with a score of over 148 is considered to be a genius.
"I was really nervous before the test and I thought it was going to be really hard. But as I started the test, I thought it was a bit easier than I thought it was going to be," she said.