Chelsea Whiteman, 13, was banned from Knole Academy, Sevenoaks, after refusing to stay in isolation for wearing the non-uniform footwear.
The Year 8 pupil was confronted by the school Principal for wearing black socks instead of white as she left school and was then placed in isolation the next day.
Her mum, Sabrina, 32, admitted her daughter could be 'mouthy' but accused the school of over-reacting.
She told her local newspaper: "Chelsea goes horse riding after school so she put her socks on just as she left school ready to put her wellies on in the car.
"Chelsea does stand up for herself, and because she was in correct uniform while in isolation she walked out, she was then excluded for a week.
"Exclusion is not the right punishment, Chelsea was probably enjoying her time off in the sun, so it isn't a deterrent. After-school detentions would work a lot better.
"Now she is just sat at home having a nice time while I'm out working.
"If she was kept after school she would miss out on going out with friends, swimming and things like that."
Principal Mary Boyle said: "We have high expectations of students and the rules of the academy are very clear to students and parents alike.
"Students are not excluded for wearing incorrect uniform, although they may be isolated from their peers.
"The academy does give short-term exclusions for defiance, failure to follow instructions and rudeness."
Which do you think are best as a deterrent - short exclusions or after-school detentions?