Out of contract this summer, Simpson will leave the King Power Stadium this summer.
He posted to Instagram: “I don't even know where to start. I never ever thought that on the day I signed for Leicester I'd play for you as long as I have, nor have as many unbelievable memories as I have, never mind ending up a Premier League winner and playing in the Champions League.
“But more importantly, I have felt at home and part of a family.
“Thank you to everyone involved with Leicester. My team-mates, the coaches, all the staff and of course the fans for your support throughout everything. I will miss giving my all for you."