The resident from Killara in the city's upper north shore held the only division one winning entry nationally in draw 1548.
The entry was unregistered, which meant officials had no way of contacting the winner until they came forward.
The instant millionaire said he couldn't believe the magnitude of his win.
"I thought I'd check the numbers on my ticket quickly and I immediately thought something was wrong when the prize came up. I sat there pondering," he told officials at the Lott.
"This is a big surprise. I'm still trying to process it all. I can't believe I've won $30 million.
"I've been in and out of the country for work, and I'm so happy to be back home in Australia.
"I haven't been able to buy an Oz Lotto ticket while working overseas and now that I've purchased this ticket, I've landed this win. I can't believe it.
"I usually only ever win $17 – nothing significant. This is significant."
Spot the error that makes this 50-cent piece worth $250
The man said an early retirement was on the cards.
"I had plans to continue to travel for work but this prize has changed everything for me," he said.
"I honestly think I might just stay here and retire. Australia is my home"
He bought his ticket at Lindfield Newsagency in Lindfield.
There are many different ways to get help and information about gambling.
Call the National Gambling Helpline on 1800 858 858; use online counselling; find information about help services in your state or territory; get information and support for family and friends; get information about how to talk with someone about their gambling; or contact Gamblers Anonymous.
All services are free, confidential and available 24 hours a day, 7 days a week.
