Serious bullying is expected to become illegal in Victoria from today.

Brodie Panlock, 19, killed herself in 2006 after enduring daily bullying from colleagues at a Hawthorn cafe where she worked.

Four men were convicted and fined between $10,000 and $45,0000 each, under the Occupational Health and Safety Act. The owner of the cafe was fined $220,000.

The teenager's death has prompted an amendment to the state's stalking laws, known as Brodie's law.

The change will mean serious workplace and online bullies can be sent to jail for up to 10 years.

The teenager's mother, Rae Panlock has welcomed the criminalisation of bullying.

"You can't play with people's minds and treat them like that and expect not to have some serious consequences," Mrs Panlock said.

"Now it's being recognised as a crime and I hope it makes people sit up and think before they engage in this sort of really serious behaviour," she said.