She went on to injure her knee at the season-ending WTA Finals in Shenzhen, China.
This ended an amazing year for her.
Here's more on Canadian star Andreescu.
'Australian Open is unfortunately too soon in my rehab process'
Andreescu added that her rehab is going well and she is feeling better with each passing day. However, the Australian Open is too soon for her.
"My rehab is going well, I feel better and stronger every day but after discussing it with my team and following the recommendation of the doctors, the Australian Open is unfortunately too soon in my rehab process."
It was a very tough decision to make, says Andreescu
"It was a very tough decision to make as I love to play in Melbourne but I have to respect the recuperation plan for my knee and body," the 19-year-old Canadian tweeted.
Andreescu compiled a remarkable 48-7 record in 2019
She has a superb 2019 season on the tennis court. The teenage sensation was ranked 178 at the start of 2019.
However, Andreescu compiled a remarkable 48-7 record and won her first Grand Slam after defeating Serena Williams in the final of the US Open at Flushing Meadows.
She also went on to win at Indian Wells and Toronto in 2019.
Andreescu's absence could ease things for title contenders
Andreescu will hope to return at Roland Garros in May 2020. Her withdrawal from the Australian Open will ease proceedings for defending champion Naomi Osaka.
The likes of Serena Williams, Ashleigh Barty and Simona Halep will be contending for the Australian Open as well.
The Australian Open is set to start from January 20 and continue until February 2.