Walker was not offered a new deal by North Melbourne for 2023 at the end of their wooden spoon finish to the season, seeing his time at Arden Street come to an end after 54 games in three years.
The forward-turned-defender started his career with Geelong, with the Cats drafting the local talent through the Rookie Draft in 2010.
The Lara product joined the Roos after four seasons with the Lions, where he claimed the club's leading goalkicker award in 2016.
After his departure from the Kanagroos, Walker nominated for the National and Rookie Drafts, however an opportunity with a fourth AFL club failed to arise.
Following the list lodgement deadline for AFL clubs, Walker took to social media to express his gratitude to play 139 matches in the league.
"Doesn't sound so bad - no more running, skin folds, ice baths etc," Walker tweeted on Friday.
Doesn’t sound so bad - no more running, skin folds, ice baths etc. Thanks to 3 great clubs that gave me the opportunity to live out a boyhood dream 139 times. Will miss the people the most but know that many of the friendships made will be for life! Excited for whatever’s next. pic.twitter.com/brX5Vy79vB
— Josh Walker (@walkerjosh14) December 1, 2022
"Thanks to 3 great clubs that gave me the opportunity to live out a boyhood dream 139 times.
"Will miss the people the most but know that many of the friendships made will be for life!
"Excited for whatever's next."
AFL clubs are still able to sign players through the Supplemental Selection Period, which will commence early next year.
North Melbourne are expected to add talent to their training program for the season ahead, with triple premiership Hawks midfielder Liam Shiels tipped to join his former coach Alastair Clarkson at the Roos.
Another ex-Hawk in Daniel Howe, who was delisted this year, was picked up by the Roos in Wednesday's Rookie Draft, while Kayne Turner landed a reprieve with North Melbourne after he was initially cut from their squad this off-season.