Queenslander Millman, who famously beat Roger Federer at the 2018 US Open, drifted out of the top 100 last August and is currently ranked 147th in the world. He reached the third round in Melbourne twice, in 2016 and 2020.
"It's a special place for me to return to, in front of my friends, family and the powerful Aussie crowd. I couldn't be more excited," Millman said in a statement.
Fourlis enjoyed a resurgent season during which she rose from outside the top 300 to a career-high world number 147 after winning 50 matches, including 12 in a row, en route to claiming three ITF titles.
Fourlis, from Melbourne, won on her Australian Open main draw debut as a 17-year-old in 2017.
"I'm so thankful to Tennis Australia for the opportunity to play in the main draw of my home Slam," said Fourlis, who reached the Australian Open mixed doubles final with Jason Kubler last year.
The final two wildcards were awarded to Japan's Moyuka Uchijima in the men's draw and Wu Yibing of China on the women's side. Both players will make their Australian Open main draw debuts.
