The Season 9 World Champion had secured Julius Baer Pole Position and started sharply to lead the pack away. The Brit kept in touch with the leaders throughout as he played the waiting game before making it by the Citroen of Nick Cassidy - who'd flown through the pack with a late charge - for what would be the definitive move on Lap 27.
HIGHLIGHTS: Catch up with every race from Formula E IN FULL
A huge shunt for rookie Pepe Marti (CUPRA KIRO) - who flew spectacularly over the top of Jaguar's Antonio Felix da Costa - and thankfully, ultimately, landed safely, meant a late Red Flag and a one-lap sprint to the finish. Dennis was able to hold off reigning champion Oliver Rowland (Nissan), who'd started all the way down in 13th - and Cassidy.
That was a first win since the trip to Diriyah in 2024 for Jake Dennis, and he becomes the first driver to win from the front row at the Anhembi Sambadrome Circuit.
Wehrlein, who had led the race, and himself had a similar incident to Marti here last season, rounded fourth with home hero Felipe Drugovich fifth on full debut for Andretti. That made it two in the top six for the American team, who played the race nicely with their late use of ATTACK MODE.
Nico Mueller rounded out the top six for Porsche having also headed the pack at points - a strong start for the Porsche-powered cars all-round with four powertrains made by the Stuttgart giants in the top six.
All that sees Dennis head the Drivers' running and Andretti the Teams' - with Porsche heading the way in the Manufacturers' table as we head to Mexico in the New Year on 10 January.
As it happened...
Dennis started sharply to hold onto the lead while the two Mahindras ran wide through the opening chicane and Dan Ticktum found himself in trouble - dropping all the way to the back of the pack on the exit of those first two corners.
That left Dennis leading Wehrlein, Mortara - who recovered after that first corner mishap - Nato, da Costa and the other Mahindra of de Vries rounding out the top six. It could have been far worse for the Indian outfit - and it was de Vries who outbraked himself into Turn 1, clipping Ticktum's CUPRA KIRO, causing a puncture and ending the Brit's chances right at the off.
Positions and the lead shuffled on Lap 3 with Wehrlein hitting the front - Dennis happy to conserve for now and slip back down the order into P4. Meanwhile, Mortara was slapped with a five-second penalty for his part in that opening corner incident - the Swiss led on Lap 4 but his race was now severely compromised.
Vergne and di Grassi were first to take the initial of their two 50kW all-wheel drive ATTACK MODE boosts while the lead again cycled on Lap 6 between former Porsche teammates da Costa and Wehrlein. Citroen's double-champ cycled back up right to the front of the pack by the time his four-minute boost expired.
Rowland was next of the top 10 to take ATTACK and saw himself right with Vergne at the end of it - scrapping for the lead and taking it on Lap 9.
Lap 11 saw leader da Costa, Evans, Nato, Mortara, Buemi and Barnard all jump for ATTACK with the order further shuffled.
When it all shook out, Wehrlein headed the way from Wehrlein, Dennis, Mortara, Nato, da Costa, Rowland, Buemi, Mueller and Evans, the top 10. The second half of the pack were all yet to jump through the activation zone for ATTACK - setting up a real race of two halves.
Lap 17 saw Rowland and Nato come to blows, with both suffering but Nato more than the Brit, coming out of it with a puncture and slipping out of contention entirely. Rowland survived to scrap on in eighth while Guenther sliced by them both.
Lap 19 and Dennis led Wehrlein and Cassidy - the Citroen new boy pulling the same tricks under ATTACK MODE to fire by half a dozen down the main straight and put himself right in the mix. A few turns later and the Kiwi had made it by Wehrlein, too - before homing in on Dennis out front.
Lap 22 saw the second round of ATTACK MODE activations begin and the order shuffle. Rowland hit top spot from Dennis, Cassidy, Wehrlein, da Costa, Mueller, Eirksson, Drugovich, Mortara and di Grassi.
One lap later, a shunt saw Mortara and di Grassi in contact at Turn 6 with the Mahindra having nowhere to go - meaning a late Safety Car and retirement for the pair.
Lap 27 and we were green once again with Rowland heading Cassidy, Dennis, Wehrlein, da Costa, Mueller, Eriksson, Drugovich, Guenther and Buemi - the Andrettis looking on for a result with energy and an ATTACK MODE activation in-hand.
Dennis made it by Cassidy and Rowland through the last sector of Lap 27 with Drugovich up to sixth.
A big shunt for Pepe Marti saw a Red Flag after the CUPRA KIRO flew over the back of da Costa's Jaguar - with Full Course Yellow thrown with the other Jaguar of Mitch Evans in the wall just prior.
The Spaniard was okay, as were da Costa and Mueller - and after the mess was cleared from the track, action got back underway with just a lap to run of the 30.
Dennis was able to comfortably head home the one-lap shootout, with Rowland following in second and Cassidy third for a debut podium for Citroen.
Find out more
UNMISSABLE: Watch the brand-new season of 'Driver' on Amazon Prime
CALENDAR: Here's every race set for the 2025/26 Formula E season
FOLLOW: Download the Formula E App on iOS or Android
TICKETS: Secure your grandstand seats and buy Formula E race tickets
HIGHLIGHTS: Catch up with every race from Formula E IN FULL
HOSPITALITY: Experience Formula E and world-class motorsport as a VIP