A statement released by the Ministry of Business, Innovation and Employment (MBIE) said CT Logistics Ltd pleaded guilty to two charges under the Health and Safety in Employment Act.
One of the charges was in relation to the injured contractor and another contractor, and the other charge in relation to its own employee.
All were exposed to the risk of harm while unloading the container, MBIE said.
The company was ordered to pay a fine of $50,000 and reparation of $5,000, on top of $10,000 already paid.
CT Logistics Ltd had failed in a number of areas, said John Howard, MBIE northern division general manager.
"This type of industry can be fast-moving and high-pressured as containers and vehicles are loaded and unloaded to tight deadlines and in confined spaces."
As well as ensuring a risk assessment had been carried out, the company should have been using the safest method for removing this type of cargo, Howard said.
It should also have kept the area clear of non-essential personnel and ensured that workers were adequately trained and supervised.
"None of these things happened, resulting in a severe injury to a worker that could easily have been avoided."
There was no excuse for the company's failings, Howard said.