The prolific attacker, who bagged 25 Bundesliga goals last term, has opted to sign a two-year extension at the Champions League hopefuls after an impressive 2012-13 campaign
The 29-year-old's previous deal with Leverkusen ran until June 2015, but the Bundesliga side were keen to reward him for his fine performances last term with a new and improved contract.
Kiessling netted 25 goals in 34 Bundesliga appearances in 2012-13 to win the top-scorer crown and Leverkusen CEO Wolfgang Holzhauser has nothing but praise for the attacker.
"Stefan has become one of our undisputed key players and leaders," he told the club's official website.
"He is our marquee signing. His development since 2006 is simply phenomenal. I hope that he will stay here until the end of his career."
The striker himself, meanwhile, was equally pleased with his new contact with the Werkself.
He added: "I am really happy. Bayer are my team and I feel really well here. Leverkusen has become my home and the conditions here are very well."
Kiessling joined Leverkusen from Nurnberg in the summer of 2006 and has since scored over 100 Bundesliga goals for B04.