Basildon Magistrates’ Court heard how the injured person, who was an employee at the company, was working at the rear of a house in Benfleet, Essex on 26 September 2014 when the incident occurred.
The 19-year-old employee had only a few minutes training on the use of the dumper truck.
He had no driving licence and was not wearing a safety belt when he overturned the vehicle.
He was airlifted to hospital where he was found to have broken his back. He spent months in hospital and his injuries are life-changing. It is not known if he will ever be able to walk again.
Oak View Tree Specialists Limited, of Rayleigh, Essex, pleaded guilty to safety breaches and was fined £3,000 with costs of £1,500.
On sentencing, HSE Inspector Keith Waller, said: “This was entirely an avoidable incident.
“The defendant failed to take reasonably practicable measures because they allowed their employee to operate a dangerous item of plant machinery with only the very minimum of training.
“It is not acceptable to put drivers into vehicles that they have not previously operated, or without the necessary training by a qualified and competent instructor.”