The director, 31, was sentenced in the Mansfield Magistrates' Court on Wednesday 2 October after pleading guilty to a single charge of failing to ensure that a workplace under their management or control was safe and without risks to health.
He was fined without conviction and also ordered to pay costs of $4,249.
In February 2022, the director and his 19-year-old apprentice had finished installing a hot water service at a property in Bridge Creek when it was decided the client would accompany them back to Mansfield.
The court heard that because there were only two seats in the director's work ute, there was a discussion about the apprentice being transported in the tool box mounted on the rear tray.
During the estimated 20-25 minute journey, the apprentice recorded a video, commenting on the discomfort and heat inside the confined space.
Upon arrival in Mansfield, the apprentice's brother witnessed him being released from the toolbox, red-faced and hunched over, as the director and client stood nearby laughing and drinking beer.
The incident was only reported several months later after the apprentice told his mother, who subsequently informed his Apprenticeships Victoria support officer.
WorkSafe's investigation found some tools had been left in the toolbox with the apprentice and that there was a risk of serious injury or death if the ute was involved in a collision or stopped suddenly.
It was reasonably practicable for the director to reduce the risk by not driving the ute, or not allowing it to be driven, when a person was in the toolbox.
WorkSafe Executive Director Health and Safety Sam Jenkin said there was no excuse for putting a young apprentice in such a vulnerable position.
"Illegally transporting this young apprentice in the back of a toolbox was extremely unsafe and could have had absolutely catastrophic consequences," Mr Jenkin said.
"WorkSafe will continue to hold employers accountable when they fail to prioritise safety and wellbeing, particularly for young workers who won't always have the confidence to speak up if something is wrong."