The Australia international defender was one of five players to be told last month that they were not part of manager Nigel Pearson's plans following the Foxes promotion back to the Championship.
Kisnorbo, who was twice voted player of the year in his four seasons at the Walkers Stadium, told the Leicester Mercury: "I'm very disappointed to have been released.
"I thought I was still good enough for the team but the gaffer said he had other plans.
"It's sad. He said he has got his own players and I have to respect that decision - it's his choice.
"I want to thank everyone for their messages of support and I want to let everyone know I'm not going because I want to."