Shoppers are also being urged to spend within their means to avoid a debt hangover in the new year.
Despite inflation and cost of living pressures squeezing household budgets, forecasts by the Australian Retailers Association expected retail sales to remain strong.
The record-high spend is set to show a 7.9 per cent increase on last year's post-Christmas shopping, which takes in the period from December 26 to January 15.
Australians are also returning to in-store shopping after health restrictions in the past two years dampened consumer confidence.
But the association's chief Paul Zahra said the days of queuing outside stores well before they opened were long gone.
"In the past it was all about being first in store, but with online shopping it's much easier to not miss out," he told AAP.
"There's more of an ease into Boxing Day sales ... it's a change in a good way as it's a much more relaxed and safer way to shop."
NSW shoppers are expected to spend the most, up an expected 9.5 per cent on 2021.
Mr Zahra said he expected this year's sales to be the biggest spend in the history of the country.
He said fashion retailers would be the most popular among this year's bargain hunters, with great clothing deals as stores look to clear inventories before winter.
After capital cities had unseasonably cold weather ahead of Christmas, Mr Zahra said retailers were keen to get their summer stock moving while online shoppers would look for bargains on household goods.
He said a large portion of home owners on fixed interest rates are yet to feel the pressure from rate increases.
The Nation Retail Association predicted a $3 billion spend in Boxing Day sales alone across Australia.
Interim chief executive Lindsay Carroll said despite the growing popularity of Black Friday and Cyber Monday, Boxing Day still reigned supreme for Australian shoppers.
Travellers looking for cheaper airfares could also be in luck with budget airline Jetstar promising sales on more than 80,000 domestic and international fares over 48 hours.
Qantas also promised discounts as part of a five-day domestic airfare sale.
But financial comparison website RateCity urged shoppers to keep track of their spending to avoid a debt hangover.
Research director Sally Tindall warned against using buy-now pay-later platforms which can create budget chaos if people don't have the means to pay the money back.
"Next year is going to be a tough one financially for many households, with more interest rate hikes lurking around the corner," she said.
"The last thing you want is to start the new year on the backfoot, surrounded by Boxing Day debts you can't repay."
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