The Belgium international initially joined the club on a loan deal from Monaco in January 2019, before making his move a permanent one ahead of the following season.
In over four years with the Foxes, Tielemans scored 28 goals and provided 26 assists in 195 appearances across all competitions.
The midfielder played the duration of Sunday's 2-1 victory over West Ham United, which proved to be of little use after Everton's win against Bournemouth confirmed Leicester's relegation to the Championship.
Tielemans has now announced via a statement on Instagram that he will leave the club when his contract expires in June.
In a message published alongside a video of his best moments in a Leicester shirt, Tielemans said: "Dear Leicester City fans, after 4.5 special years and with a lot of gratitude I'm bidding farewell to this incredible club.
"From the first day I set foot on this ground, your warmth and passion embraced me. Victory and triumph, love, hope and even defeat.
"We've shared many special moments together. I am forever grateful for your unwavering support.
"Thank you to Khun Top (Chairman), the board, the staff, the players and fans for having given me and my family a home. This is not a goodbye, but a heartfelt farewell."
Tielemans was Liecester's hero in the 2020-21 FA Cup final against Chelsea, scoring the only goal of the game with a stunning strike
The Belgian is expected to be one of several players that will leave the King Power Stadium following a disappointing campaign.
Caglar Soyuncu is expected to sign for Atletico Madrid on a free transfer, while the likes of Ryan Bertrand and Jonny Evans are also out of contract.
Harvey Barnes and James Maddison are also set to leave this summer, with Tottenham Hotspur and Newcastle United interested in signing the pair.