Omer Toprak's first Bundesliga goal also helped Sami Hyypia and Sascha Lewandowski's men clinch at least third place in the Bundesliga, rendering Sidney Sam's late penalty miss only cosmetic.
Nuremberg once again missed the chance to break through the 40-point barrier, although they were at least able to celebrate mathematical safety with two games of the season to spare.
Both sides had good early chances with Niklas Stark striking the outside of the post for Nuremberg, albeit after the ball had already crossed the goal line, and Andre Schurrle shot just wide from a tight angle.
The chances continued to fall at both ends with Stefan Reinartz setting up Sebastian Boenisch, whose shot missed the goal by inches.
Alexander Esswein's distance effort gave Bernd Leno a handful in the 17th minute with the Leverkusen custodian somehow managing to turn the ball behind.
Leverkusen took the lead in the 26th minute with Toprak's first Bundesliga goal in his 89th appearance.
His powerful point-blank header left Raphael Schafer no chance as he met Gonzalo Castro's pinpoint cross to break the deadlock.
He almost did the same again from a corner in the 33rd minute, but his effort missed the target.
Just before half-time, Leno denied Nuremberg an equaliser with a fine one-armed save to turn Esswein's shot over the crossbar with Stark heading the ball wide from the resulting corner.
Sam lifted an effort over Schafer, but onto the roof of the net early in the second half before sending another shot just over the crossbar as Leverkusen looked to finish off their hosts.
They did that in the 62nd minute when Per Nilsson handled the ball in the area and a penalty was given.
Kiessling stepped up to score his 23rd goal of the season, making him Leverkusen's record goalscorer for a single season, breaking a record he shared with Ulf Kirsten.
The Germany striker was still on the field, but not on the spot in the 81st minute when Leverkusen were awarded another penalty.
Instead, Sam stepped up, but he struck the left-hand post and, almost as a punishment for the way in which he had stolen the ball off Kiessling to take the penalty, he was substituted with Daniel Schwaab coming on.