The Kiwi didn’t set a lap time in the morning practice session due to a brake-by-wire failure, but he went on to set a 1:09.871 to secure pole by a tenth and a half from Maximilian Gunther.
The top three in the championship are now covered by just four points. Pascal Wehrlein leads the way with 180 points, Mitch Evans is on 177, with Cassidy one point behind on 176.
Gunther splits the championship trio in second place. The German driver set a 1:10.040 in the final.
Mitch Evans failed to get into the final after losing a highly competitive semi-final to Gunther. Evans lost the duel by half a tenth after setting a 1:10.278. The Kiwi will start from third.
Championship leader Pascal Wehrlein will start the race from fourth place after losing to Cassidy in the semi-final. The Porsche driver set a 1:10.428.
Robin Frijns will start in fifth place for Envision Racing after being knocked out by Cassidy.
Jean-Eric Vergne will start in sixth place for DS Penske after being knocked out by Gunther.
Stoffel Vandoorne will start in seventh in his final race for DS Penske after being knocked out by Evans in the quarter-final.
Sam Bird will start in eighth after being knocked out by Wehrlein in the quarter-final stage of qualifying, setting a 1:10.598.
Oliver Rowland and Antonio Felix Da Costa just missed out on the duels stages, as both drivers were fifth in their groups. Rowland starts in 9th and Da Costa in 10th.
The Mahindra duo finished yesterday’s race in fourth and fifth but were unable to replicate that in qualifying, with Mortara starting in 20th and Nyck De Vries in 22nd.
Reigning World Champion Jake Dennis will start on the back row of the grid after being the slowest driver in Group A. He will start in 21st
