Austin, 32, has spent the last six seasons with Pools but has opted to move on after being offered reduced terms at the end of last season.
“I would like to thank the fans for their support during the time I have been here and for their loyalty,” Austin told the club’s official website.
“To go through what they have been through over the last three years and still keep coming in their numbers is amazing.
“Away from home the support has been incredible too and I have to say I think you will struggle to find more loyal fans anywhere in the country so I wish them all the best.”
Austin joined Pools in the summer of 2009 from local rivals Darlington and made 248 appearances, scoring 12 goals.
Pools overturned a 10-point gap from safety last season to secure their Football League status with a game to spare thanks to a 2-1 win against Exeter in their final home game.
Austin added: “I think that feeling after the Exeter game was up there with the best I’ve ever had in football – I was certainly more emotional than when I got promoted with Barnsley.
“It’s the first time I have had tears in my eyes on a football pitch.”