The 30-year-old joined the Magpies last summer from Gibraltar Premier Division outfit Europa FC.
Walker has made 19 appearances this season but has found himself on the fringes of the team and in recent weeks struggled even to make the bench.
Notts confirmed the news of Walker's contract being terminated by mutual consent on Monday afternoon, stating that he had left "with immediate effect to pursue opportunities elsewhere".
Manager Kevin Nolan also left a brief message for the midfielder.
“Everyone at Meadow Lane would like to thank Liam for all his efforts this season," Nolan was quoted as saying. "We wish him all the best for the future.”
Share your thoughts about this news story on Pride of Nottingham by signing up to the website, visiting the forum and joining in the chat with hundreds of fellow Notts County fans.
Fancy showcasing your brand or business on Pride of Nottingham? Click here to find out more about sponsorship and advertising opportunities with us.