On his team's home turf, Andretti driver Dennis produced a lap of 1m08.931s in the pole shootout to beat Nissan rival Fenestraz by a scant 0.079s.
It gives him three bonus points that puts him two points clear of erstwhile leader Pascal Wehrlein at the head of the standings heading into Saturday's race.
Fenestraz had the better start to the lap of the two finalists, having been half a tenth up after sector two, but a poor final sector allowed Dennis to claw back the lost ground and take pole for the first time since last year's London E-Prix.
Making up the second row of the grid will be Fenestraz's Nissan team-mate Norman Nato and McLaren's Rene Rast.
Having dispatched Maximilian Guenther in the quarter-finals, Fenestraz was up against Nato in the first of the semi-finals, but eased through to the final with the first sub-1m09s effort of the weekend, a 1m08.920s, to beat Nato by 0.344s.
In the second semi, Dennis eclipsed Fenestraz's benchmark by a single thousandth of a second, to beat Rast by a comfortable 0.455s and book his third consecutive final appearance.
Earlier on, Dennis beat the other McLaren of Jake Hughes in the quarter-finals to become the only non-Nissan powertrain user to reach the last four.
Maserati MSG man Guenther will line up fifth ahead of Hughes and Porsche's Antonio Felix da Costa, who lost out to Rast in his quarter-final.
The other driver to make it out the group stages was Jean-Eric Vergne, but he and his DS Penske team-mate Stoffel Vandoorne will both start Saturday's race from the pitlane.
Source: Autosport