The 26-year-old, who has scored 16 times in the league this season, said he wanted to stay with the club he joined in 2006 to taste success. His current deal was due to run out in 2012.
"I feel very comfortable with my family and the club has in the long term outstanding prospects so I see no reason to change anything," Kiessling, who is expected to feature in Germany's squad for this year's World Cup, said in a statement.
He has been in sparkling form, combining superbly with fellow striker Eren Derdiyok and playmaker Toni Kroos to take third-placed Leverkusen into the final stretch as title contenders.
"We are delighted to have kept one of the best German strikers," Leverkusen managing director Wolfgang Holzhaeuser said. "We had agreed in principle for some time now and we have now finalised all issues."
The 1.91 metres-tall Kiessling, who is as effective in the air as he is scoring with long-range strikes, has only three caps but is expected to win many more with a call-up for the World Cup squad almost certain.
Leverkusen, who led the standings for much of the season, have 53 points and trail leaders Bayern Munich by three points and second-placed Schalke 04 by just one after 26 games.
