The Recorder James Mulholland QC handed down a six month prison sentence to Natasha Haley, but suspended it for 12 months, saying he did not want to deprive her children of their mother.
Ms Haley took action against a group of youths after her 11-year-old son was beaten and robbed.
Ms Haley was said to have snapped last November after contacting the school and the police about a group assault on the school bus, name calling and other 'unpleasant' incidents involving her son.
Her lawyer Michael Smalley told the court that Ms Haley's son was upset and did not want to return to school after being assaulted; when he did go back, he was robbed in one of the classrooms.
Ms Haley felt that despite reporting the attacks, no action was being taken.
Mr Smalley said: "She accepts she went over the top. She has remorse and regret. She says she was stupid."
The mum admitted affray and was given a six month prison sentence suspended for 12 months, put under curfew, and ordered to carry out 150 hours' unpaid work.
Mr Mulholland said he sympathised over the "horrific" bullying but said Ms Haley had "gone off the scale" with her actions.
He told Maidstone Crown Court: "It is so far removed from what one would hope a parent would do."
Speaking after the hearing, Ms Haley said: "The driver smiled at me and said nothing as he thought I was within my rights."
"I should never have got on the bus with the baseball bat. I should have gone to the parents' house and spoken to them instead."
"I would never touch a child. I'd never dream of it in a million years."
She also revealed she was planning to sue the school as 'nothing had been done about my son being bullied.'
A police spokesman said the initial assault on Ms Haley's son was was "resolved without further police involvement."
What do you think about this story?
Can you totally understand this mum's frustration, or do you think the judge should have jailed her?