The girl's injuries were not life-threatening, but she required hospital treatment, while the woman sustained "more minor" injuries, according to domestic outlets.
An 11-year-old girl and a 34-year-old woman have been stabbed in London's central Leicester Square.
A man has been arrested and is currently being held in custody, according to the UK capital's Metropolitan police.
"We don't believe there are any outstanding suspects," the police force posted on X.
The woman and the girl were taken to the hospital. The girl's injuries were not life-threatening, but she required hospital treatment, while the woman sustained "more minor" injuries, according to domestic outlets.
Photos on social media show a police cordon near a well-known toy store on the square, a popular tourist destination.
There were no immediate indications of a terrorist act, the Metropolitan police said.
Our journalists are working on this story and will publish more information shortly.