The striker was this week included in DR Congo's squad for their meeting with Morocco and he slotted home his fourth goal in as many games in the 28th minute in Paisley.
Killie dominated possession in the first half and Kabamba dispatched their first chance when he converted Chris Burke's low cross as the Ayrshire side moved into the Scottish Premiership top six.
Lee Erwin had earlier headed against the bar for St Mirren but the hosts could not carve out a meaningful opportunity to level and avert a fifth consecutive defeat.
St Mirren have had disruption in their rearguard throughout their losing run and, although Jim Goodwin welcomed back goalkeeper Jak Alnwick following a bout of Covid-19, full-back Richard Tait started a two-match ban.
Marcus Fraser switched to left-back and Cammy MacPherson came in at right-back. Goodwin also brought in Junior Morias and Ilkay Durmus on the flanks.
Killie also had a suspension to deal with following Eamonn Brophy's red card against Hamilton but Alan Power returned from injury as Alex Dyer added an extra man in midfield.
The visitors quickly exerted control of the game but St Mirren had the first chance 10 minutes in as they countered following a Killie corner. Durmus was one on one with Ross Millen and got a shot away but was just off target.
The hosts came closer midway through the half when Erwin met a Durmus corner 16 yards out and sent a powerful header off the bar.
Dyer's team opened the scoring from their first chance. Chris Burke got in behind down the right following a give-and-go with Alan Power and sent in a low cross. Kabamba got in front of Conor McCarthy to strike home from eight yards.
St Mirren had another chance from a set-piece when Danny Rogers dropped a Durmus corner but Joe Shaughnessy could not keep his effort down.
Goodwin made a double half-time switch. Jon Obika joined Erwin up front and Nathan Sheron came into a midfield vacated by Sam Foley and Jamie McGrath.
The game was almost beyond them inside four minutes after a brilliant move. Greg Kiltie ran on to Millen's return pass and swept a shot from 18 yards which Alnwick tipped wide.
After getting Shaughnessy and Tait sent off in recent weeks, Goodwin must have feared the worst when Fraser planted his studs in Burke's chest, but referee David Munro decided a yellow card was sufficient.
Saints brought on wingers Dylan Connolly and Kyle McAllister but Kilmarnock survived some belated pressure without Rogers being called into serious action.