Rush produced the fastest time of the first runs in France, 1:00.63, however just seven hundredths of a second separated him in first with Jackson in fourth at the halfway stage.
However there was to be no denying the 31-year-old Canadian as he kept his nerve to go even quicker, posting 1:00.55, second time out to win by almost three tenths of a second.
Rush, alongside Jesse Lumsden, produced a winning time of 2:01.18 to beat Switzerland's Beat Hefti, who remained second throughout in La Plagne, by 0.27 seconds.
American Steven Holcomb, who won the first three races before making way for Hefti in Winterberg last time out, jumped up from sixth at the halfway stage to claim third.
And, while Holcomb was rising up the rankings, Brit Jackson, alongside Bruce Tasker, fell from fourth to eighth overall after going more than half a second slower on their second run.
Still that marked Jackson's best finish in the two-man this season while fellow Brits Lamin Deen and Ben Simons marked their first World Cup appearance of the campaign by finishing 27th.
- Sports & Recreation
- Beat Hefti
- Jesse Lumsden