Anne Winston, from Cardiff, broke the world record for reciting the details of all 195 countries in seven minutes and 15 seconds.
The year three pupil, from Pontprennau Primary School, said her interest was piqued five years ago when her father began telling her about different countries around the globe on their journeys to and from nursery.
Anne was three at the time, and as she moved from nursery to school she began to teach herself.
She said: “My learning was quite casual, initially on a weekly basis where I used to spend 15 to 20 minutes learning a new set of capitals and currencies.
“Towards the end, I was practising on a daily basis.”
Anne beat the previous 10-year-old record holder in a live-streamed event organised by OMG Book of World Records.
She said she was “delighted” and dedicated the achievement to her grandfather who died recently.
Her parents, Jacob and Jincy Winston, said: “From a very young age we noticed Anne had a talent for retaining information and all we did was further feed into that.
“At no point in our journey till now did we even dream of attempting a world record, let alone achieving it.
“Words cannot describe our emotions and joy and we truly hope that this leads to her achieving greater heights in the future.”
Pontprennau headteacher Ian James said: “Anne is an incredible young girl who adores all aspects of her learning. Her world record demonstrates her superb memory skills and general knowledge.
“It is a privilege to have Anne as one of our pupils.”