The 30-year-old Cologne native, whose existing deal was due to run out in the summer, has been at the club since his youth - save loan spells at FC St. Pauli (2010/11) and Eintracht Frankfurt (2011/12).
'An integral part of my life'
"I had no doubts about extending for another three years," Kessler said. "It's an absolute dream for me to have been under contract here for over half my life. The club has been an integral part of my life since I was a kid."
Kessler has made six Bundesliga appearances for Köln, as well as nine in Bundesliga 2. The former Germany Under-18 international is currently Billy Goats first-choice goalkeeper Timo Horn's backup.