Kalou's second-half strike put the Blues on the road to victory against the team managed by former Stamford Bridge idol, Gianfranco Zola, and then the Czech Republic keeper saved Mark Noble's penalty to extend his side's unbeaten run to seven games.
Wednesday night's goalless draw with Everton may have already extinguished Chelsea's flickering title aspirations, but Guus Hiddink still harbours hopes of landing FA Cup and Champions League silverware before he departs these shores at the end of May.
And with one eye on their forthcoming midweek Champions League semi-final in Barcelona, the Dutchman made five changes to the side that had come unstuck against the Toffees, as Michael Mancienne, Jose Bosingwa, Juliano Belletti, John Obi Mikel and Kalou were each handed starts.
Indeed, Kalou almost repaid his manager's faith in him inside the opening minute, when he sent a rising 20-yarder sizzling past Robert Green's right-hand angle and, on the quarter-hour mark, the man from the Ivory Coast then raced into the box and drilled an angled shot just inches beyond the far post.
Following their draw at Aston Villa last Saturday, Zola made just one enforced change to his seventh-placed side as Kieron Dyer came in for James Collins (calf) and, likewise, the fit-again England midfielder had West Ham's first decent chance of the opening half, but with just Cech to beat, he fired straight at the towering keeper.
That was to prove a rare opportunity for the Hammers, whose blunt strike pairing of two, tiring 33-year-olds - in the shape of David Di Michele and Diego Tristan - failed to inflict any damage on John Terry and the rest of the visitors' defence.
At the other end, with Chelsea mopping every loose ball, Matthew Upson, Lucas Neill, James Tomkins and Herita Ilunga defended for their lives, as Florent Malouda, ex-Hammer Frank Lampard, Nicolas Anelka and Kalou each threatened to put the Blues ahead.
But, ironically, it was West Ham, who almost broke the deadlock, three minutes before the interval, when Tomkins nodded Noble's corner down for Tristan, whose weak goalbound prod was booted off the line by Mikel to keep it all-square at the break.
That was to prove an expensive miss by the former Spain international striker, for ten minutes after the restart, Chelsea struck the killer blow.
The heavily lambasted Lampard, got to the byline before scooping the ball over a handful of defenders towards the far post, where the unmarked Kalou, six yards out, sent his shot high into the roof of the net.
That was the cue for Ashley Cole to replace Bosingwa, while Zola introduced Freddie Sears, Radoslav Kovac and then Savio Nsereko at the expense of Dyer, Di Michele and Luis Boa Morte.
The outstretched legs of Green denied the breaking Anelka before Cole deposited an angled effort onto the top of the crossbar.
With 20 minutes remaining, though, West Ham were presented with a golden opportunity to claw themselves back into the contest, when Ilunga tumbled under the challenge of Kalou.
But with the luminous, orange-shirted Cech cutting an imposing figure between the posts, Noble saw his penalty clawed around the keeper's left-hand post, to keep Chelsea's three points intact.