TAB executive chair Dean McKenzie told Stuff that according to their records, it is their biggest payout.
"Looking back as far as 2013, the next biggest Melbourne Cup win was $364,016," McKenzie said.
"The man received $38,939.50 for every dollar he bet."
The sum can act as a reward for the man's ongoing loyalty. Bishopdale TAB manager Kerralyn Hooper told Stuff he has been a customer for a long time.
"The customer is well known to us and a really nice guy so we are just thrilled for him," she said.
"I have been involved with the TAB for 25 years and I have never seen anything like it.
"It was just surreal to see somebody win that amount of money. We were so excited for him. I think initially our excitement was higher than his because he was still in shock."
Bets for the Cup totalled $11.5 million in New Zealand, also a new record. The previous record was $10.3 million, set in 2018.