The alleged victim, Ann Njeri, who runs a restaurant in the town told police that they had been drinking at a pub with the Daegu champion, before he offered to drop her to her parents home in West Indies, in the outskirts of the town.
But before she could alight, the woman claims they differed prompting a confrontation during which the athlete allegedly stabbed her on the left side of the chest.
The woman is now admitted to the Med Hill Hospital in Eldoret.
Local Police say the athlete later presented himself to the station and claimed that he had been attacked.
A police investigation is underway on the matter.
Rift Valley Provincial Police chief Francis Munyambu has confirmed the incident but says they have not established all the relevant facts about it.
Kemboi booked his place in the London Olympics squad by finishing second at the Kenyan Trials on Saturday where he impressed the crowd by re-enacting his Pamela Chepchumba dance while also imitating the Usain Bolt arrow.
When contacted, Team Kenya management said they were establishing the matter before issuing a formal response.
- Report by Bernard Momanyi and Mutwiri Mutuota