Kalou, who had not scored so far this season, showed what he was all about as he sealed his hat-trick before the end of the second half after netting twice in the first half.
Christoph Kramer was also sent off for the visitors in the first half after receiving two yellow cards, who lost yet again to leave Andre Schubert with a lot of questions to answer.
Kalou opened his account for the season for the hosts
It was a first half that started with the visitors on the front foot looking dangerous but as it went on it turned into a disaster.
The foals showed glimpses of what they could do on the break early on against the hosts by hitting them on quick breaks but were let down by the final ball.
Then out of nowhere, a brilliant cross was whipped into the box by Mitchell Weiser for the hosts and Kalou was there at the back post to power his header past Yann Sommer.
From there the tide of the game changed as another mistake after the half-hour mark allowed Kalou to score his second of the game. A clearance from Nico Elvedi rebounded off one of his own players and Kalou made no mistake by slotting the ball home to leave the visitors with a huge amount to do.
Visitors down to ten men after Kramer sending off
It got even worse for the visitors though as they were reduced to ten men five minutes before half-time. Kramer, who was booked early on for stopping a counter attack, committed another similar foul and was shown a second yellow straight away by Tobias Stieler.
Therefore at half-time, even though they hadn't really created much throughout the half, the old lady were in firm control of the match and would have been thinking they could get more goals in the second half.
Visitors show fight
To be fair to the visitors though they came out in the second half and made a couple of changes to the team which made it difficult for the hosts to make their extra man count on the pitch.
They gained confidence from this and almost got a goal back on a number of occasions during the second half. The first real chance fell to Fabian Johnson, who was through on goal but was stopped by a last-ditch tackle by Niklas Stark.
Jannik Vestergaard also went close for the visitors but saw a powerful header well saved by Rune Jarstein, who then made a great save to deny Lars Stindl a few minutes later, who almost finished off a wonderful team move.
Kalou scored his third late on as the hosts moved up to third
The problem though for the visitors was that as they pushed forward to try and get back into the game, the hosts finally sealed the three points before the end of the game.
Kalou was the man again to complete his hat-trick as a wonderful through ball from Weiser found the striker, who once again showed his class in front of goal to slot home past the helpless Sommer.
That was to be the last meaningful action of the game as the hosts moved themselves up to third in the table for the time being.