The 31-year-old Spaniard has not played since he withdrew from the season-ending World Tour Finals in London in November with a knee injury. He had already withdrawn from an exhibition tournament in Abu Dhabi that starts later on Thursday.
"I am sorry to announce I won't be coming to Brisbane this year," Nadal said on his Twitter account.
"My intention was to play but I am still not ready after last year's long season and the late start of my preparation."
The Brisbane tournament was due to start on Sunday.
Nadal, who also cancelled a training block last week, returned from injury last year to reach the final of the Australian Open and win the titles at the French and U.S. Opens.
He played in Brisbane last year as part of his preparations for Melbourne Park and made the quarter-finals before losing to Canada's Milos Raonic.
"I had a great time there (in 2017) and it was a great start to the month I spent in Australia," Nadal added.
"I will be seeing my Aussie fans when I land on the 4th in Melbourne and start there my preparation for the Australian Open."
The Australian Open runs from Jan. 15-28.
(Reporting by Greg Stutchbury in Wellington; Editing by Nick Mulvenney)
