In January he joined Al Jazira in the United Arab Emirates on loan until the end of the season.
Lewis, 28, joined on a free transfer from Peterborough United in 2012 but made only five senior appearances and had loan spells with Blackpool and Fulham.
Slovenia international striker Velikonja joined Cardiff on a four-year deal in July 2012 but failed to score in five first team games for the Bluebirds
Slovakian Kiss joined Cardiff on loan from SK Slovan Bratislava in July 2011 before the deal was made permanent 12 months later.
The 25-year-old spent two loan spells at Ross County and also spent a season on loan with Norwegian side.
Cardiff have also released Jazzi Barnum-Bobb, Abdi Noor, Tyler Roche and Curtis Watkins from their developmental side.
However, extensions have been offered to Luke O’Reilly, Elijah Phipps, Jamie Veale, Macauley Southam, David Tutonda, Ashley Baker, Dylan Rees, Tom James, Robbie Patten, Tommy O’Sullivan and Theo Wharton.
Jamie Bird, Rhys Abbruzzese, Lloyd Humphries and Rollin Menayese have all been offered their first professional contracts.