He left them at the depot and a colleague delivered them the following day.
Some of Mr Clode's co-workers complained to his team leader Deslys Tredrea about what happened, the ruling said.
In a meeting to explain his actions, Mr Clode said he believed NZ Post's reaction was disproportionate, considering he had delivered 500 other circulars, three of the shops were shut that day, and he believed he had five days to deliver them.
Ms Tredrea rejected his explanation and pointed to rules that stated circulars needed to be delivered on the day it had been agreed they would be delivered, the authority said.
Mr Clode said he had not seen the rules and the authority found that NZ Post did not provide any evidence that he had seen them.
He was dismissed for serious misconduct on April 2 last year.
"Ms Tredrea has relied on concluding that Mr Clode deliberately failed to follow a directive...and deliberately failed to deliver the circulars," the ruling said.
Authority member Paul Stapp said there was no evidence that Mr Clode's behaviour was deliberate.
He said Mr Clode "genuinely believed that he had five days to deliver the circulars and that there would not be any impact on the businesses that were shut for the day".
"I hold that New Zealand Post has not been able to justify the decision to dismiss Mr Clode on the grounds of serious misconduct."
However, Mr Stapp said Mr Clode did contribute to the situation because of his "intemperate" comment about not delivering the circulars.
Mr Clode was awarded $9327.82 in lost wages and $4500 in compensation.
Neither NZ Post nor Mr Clode were immediately available for comment.
An NZ Post spokeswoman said they would not be appealing the ruling.
"We are complying with the determination and will work towards Mr Clode's reinstatement."