Muguga Primary School standard five pupil Beth Muthoni was found dead in her father's house on Thursday morning following an alleged family dispute.
Muthoni's parents separated last Monday and her mother Rhoda Nyambura rented a house near her husband's home as they settled their disagreement.
The girl's father Amos Kinyanjui said that on Wednesday evening the mother sent Muthoni to a nearby shop to buy charcoal but instead the girl went to her father's house, since she knew he wasn't there, and hanged herself in her room.
In a statement sent to the newsroom, Kinyanjui said it was past midnight when he heard his wife looking for their daughter only to check in the room and discover her dangling body.
"That is when I raised alarm and shouted and people came and saw it," he said.
Kiambu County Police Commander James Mugera said police are investigating the incident to establish why the girl hanged herself.