Although Dennis had blazed his way to the final with an impressive 1m37.997s to go half a second clear of his semi-final opponent - race 1 winner Mitch Evans - he was unable to repeat those heroics in the final.
Vergne was able to keep it clean as Dennis got a bit out of shape in the first sector and, although the Avalanche Andretti driver had recouped some of the deficit in the final sector, it was not enough to deny Vergne pole position.
The pole lap that Vergne registered in the final stood at a 1m38.268s, just over a tenth slower than his lap from his semi-final against friend and former teammate Andre Lotterer, which the Frenchman edged by 0.2s.
Vergne's quarter-final bout against Robin Frijns was also closely contested, with Frijns having the upper hand in the opening sector by over a tenth of a second.
But Vergne chipped away at the Dutchman, taking a smidgen of time out of him in the second sector, before leaping above in the times in the final sector by just under a tenth overall.
Lotterer dispatched Stoffel Vandoorne in their quarter-final duel, the two separated by under a tenth through the opening brace of sectors before Vandoorne ran out of steam in the final part of the lap, ending the laps 0.3s off Lotterer.
But Porsche endured a reversal in the next heat, with Pascal Wehrlein dumped out of the duels by Dennis by a similar margin.
The semi-final lap from Lotterer was good enough to collect third on the grid, ahead of Evans.
Evans, off the back of yesterday's impressive victory from ninth on the grid, made his first duels appearance by topping the Group B times - where he was drawn against Jaguar teammate Sam Bird in the quarter finals.
Bird will start from fifth having set the fastest time of the quarter-final eliminated drivers, lining up alongside Frijns - the Envision driver just 0.008s slower than the British veteran. Wehrlein will start from seventh, joining Vandoorne on the fourth row.
Nyck de Vries and Edoardo Mortara were the biggest scalps claimed in Group A, with de Vries missing out on a place in the duels by 0.005s as Bird crept in ahead of the Dutchman.
De Vries endured a small slide at Turn 9 as he transcended the limits of grip available, losing a smidgen of time in the middle sector which proved to end his chances of making the top eight - and his misery will be compounded with a three-place grid penalty for his Race 1 contact with Pascal Wehrlein.
Mortara was also fractions off of making the top four, sitting 0.033s behind Bird, but the championship leader had to endure the ignominy of missing out for the second race in a row.
Dan Ticktum was unable to replicate his pace in free practice and, despite a strong first sector, was unable to keep his NIO 333 hooked up enough to bother the top four.
Antonio Felix da Costa was dumped out in Group B with a late lap from Wehrlein, with Vergne on the cusp of being eliminated from the top four as Sergio Sette Camara was dazzling on board of his Dragon Penske car before the Brazilian locked up and crashed at the chicane.
Sette Camara was third after the first set of runs, but was unable to deliver at the final moment and missed out on booking his and Dragon's first duels appearance.
However, he starts alongside da Costa on the fifth row owing to de Vries' grid penalty.
Lucas di Grassi also missed out to compound Venturi's misery, scraping the wall on his first run and ending up with a piece of advertising hoarding wrapped around his rear wing fender.
