Cardiff will allow long-serving Kevin McNaughton to leave this summer along with Danny Gabbidon and Nicky Maynard.
Highly-rated Atletico Madrid midfielder Saul Niguez has signed a new five-year contract.
Sheffield Wednesday have secured the services of Rafael Floro on a one-year deal following a successful trial period with the club.
The 19-year-old left-back has impressed during the Owls' pre-season and has now been rewarded with a contract at Hillsborough.
Floro has represented Portugal at Under-18 level.