The offender ran towards the officer with a knife in his hand.
The officer quickly got out of his patrol car, leaving the engine running.
He drew his Glock pistol and repeatedly told the man to drop his knife before shooting him in the arm.
The officer later told the police the offender was taking big running strides towards him.
"We locked eyes as he ran towards me with the knife... [He] appeared focused and was locked on me like nothing else mattered to him but getting to me.
"At this point I believed that he was charging at me with intent in killing or very seriously injuring me.
"I knew that if he was able to contact me with the knife he held in his hand that he could
very well kill me. I feared for my life."
A photographer parked nearby and local resident who witnessed the incident both
saw the offender run towards the patrol car and jump on to the bonnet.
The offender then got into the driver's seat of the police car, revved the engine, and tried to get the car into gear.
The officer presented his Glock pistol at the man through the closed window and told him to get out and on to the ground.
The man complied. He was arrested and received medical treatment.
One of the witnesses told the IPCA the driver was "definitely a danger" and agreed the officer "needed to do something".
The offender was later convicted of aggravated robbery, driving offences and assault with a weapon.
The IPCA found the officer's use of force was justified because he genuinely believed the offender would seriously injure or kill him.
The non-fatal shooting was deemed to be in self-defence.
IPCA chair Judge Colin Doherty said the offender had repeatedly ignored the officer's instructions, advancing on him.
"The officer subsequently fired a shot in self-defence, which was reasonable in the circumstances," he said.
"When the man got into the patrol car, the officer was aware of the risks, and acted swiftly to stop him from accessing the firearm lock box and driving off."
Inspector Freda Grace, Acting Tasman District Commander, said use of force by police officers was always a last resort.
"This was a fast-moving and evolving situation, in which the officers involved made judgment calls that were supported by the IPCA," Grace said.
"In this instance, the IPCA notes that communication had no effect on the man's behaviour and the officer genuinely feared for his life, and fired a shot in self-defence.
"Our officers' safety is paramount and we want all our officers to be safe while they are doing their jobs."