Hardiman made her last appearance in Round 4 in AFLW Season Seven, having dealt with a knee complaint at the beginning of the season.
Kangaroos' head of women's football Nathan Hrovat held high praise for Hardiman as he addressed the news on Tuesday.
"Dani has been an important and much-loved member of the side both on and off the field since our first season in 2019," he said.
"She epitomised the Kangaroo spirit and her devotion to the team and the program was second to none. We will certainly miss having her around the club.
"We thank Dani for her fantastic contribution to our program during her five seasons in the blue and white and wish her all the best in life post-football. As an inaugural Roo, she will always be a special part of our history and will always be welcome at Arden St."
The departure of Hardiman has created a list spot for the Kangaroos ahead of AFLW's eighth season.