Potters' boss Tony Pulis is a long-term admirer of 26-year-old Walters and had a £3m bid rejected in 2008.
Pulis has continued to monitor the former Blackburn and Bolton striker who cost Ipswich just £100,000 from Chester in 2007.
Stoke assistant boss Peter Reid was at Portman Road on Sunday to check on Walters in the 3-0 home defeat by Sheffield United.
"He has been amazing this year, his captaincy has been excellent and he's been a joy to work with.
"But we have a core group of players we have no intention of letting go, my captain being one of them."