The German driver made a pass on longtime leader Sam Bird to collect the lead, and was able to resist Dennis' advances in order to chalk up his first win of the season in Saudi Arabia.
Having made up three places on the first lap after benefitting from a first-lap pile-up between Mitch Evans, Lucas di Grassi and Oliver Rowland, Wehrlein made up another place on the eighth lap when Rene Rast went too wide into the Turn 18 chicane.
The Porsche driver waited until lap 13 to take his first attack mode, opting for a three-minute dose to start with, which brought him close enough to pass Jake Hughes when the Briton grabbed his first activation.
With great pace, Wehrlein then caught polesitter Sebastien Buemi - who had been passed by Bird on the seventh lap - and then nipped past once the Envision racer had gone off line to accept his first power boost on lap 23.
This put Wehrlein on the stage to contend for victory, and he immediately filled Bird's mirrors with his black and red Porsche in his bid to make a play for the lead.
Wehrlein looked to have taken it on the 25th tour as he dived past Bird at the Turn 18 chicane, but he overcooked it under braking and went into the run-off to hand Bird a reprieve.
This put Bird into a more defensive mindset and, on the subsequent four laps, he took to the middle of the road on the run to the chicane to ensure Wehrlein would have to go around the outside.
But the siege from Wehrlein did not abate, and the German forced a successful attack on Bird on lap 30 with a near carbon copy of his attempt earlier on - but sans lock-up to ensure the lead was secured.
With more energy than Bird, Wehrlein was able to make hay and put a gap on the Jaguar driver, which left the latter under attack from the charging Dennis after the Andretti driver had cleared the McLarens and Envisions.
Dennis then cleared Bird on lap 34 at Turn 18, and was immediately thrust behind Wehrlein as the Porsche driver collected his final minute of attack mode.
Told on the radio that he was half-a-percent behind Dennis on useable energy, Wehrlein had to box clever to remain in front, particularly when the Mexico City E-Prix winner had a look on the penultimate lap.
Wehrlein had saved enough to hold firm on the final lap, however, and despite Dennis considering a move into the final corner, the win was Wehrlein's.
Dennis had been equally impressive in his rise through the field having started 11th, and won out in an early battle with di Grassi to start his ascent through the order.
He picked his way past Nick Cassidy to get onto the back of Hughes, who was struggling for pace in race trim after a strong qualifying performance that took him to second on the grid.
Once Hughes picked up his second attack mode, Dennis was through and then cleared his namesake's McLaren team-mate Rast to join the battle for the podium.
Buemi was next on the agenda, as the Swiss had been unable to cling to the battle for the lead despite his starring turn in qualifying, and a late attack mode strategy failed to pay off as Dennis swept past at the chicane while Buemi was on the attack mode loop to get into the top three.
In the meantime, Bird had dropped away from Wehrlein and was easy pickings as the Porsche-powered cars showed great efficiency in the race, with Dennis claiming second on lap 34.
Although Wehrlein was in close proximity, the Warwickshire native could not find his way through and had to be content with second - admitting after the race that a podium finish had been a surprise.
Three seconds behind, Bird completed the top three to claim his first podium since the 2020-21 season, having led the majority of the race's first half, while Buemi claimed fourth to continue his strong start to life with Envision.
Rast claimed fifth to chalk up the first points of his Formula E return, but was almost collected by Cassidy at the line as the McLaren had to slow having been tight on energy at the climax of the race.
Jean-Eric Vergne picked up his first points of the year with seventh, ahead of an ailing Hughes, as Lotterer collected ninth after Mitch Evans was handed a five-second penalty for causing the lap 1 incident.
Evans had locked up and hit Rast and then veered into Rowland, causing di Grassi to check up and put Antonio Felix da Costa into the wall - a repeat of last year for the Portuguese who had endured a similar first-lap incident with Dan Ticktum last year.
Maximilian Guenther was unable to take to the start of the race following his hefty crash in group qualifying, having damaged the tub of his car, continuing a miserable day for Maserati MSG racing - while Edoardo Mortara retired in the other car.
Formula E Diriyah E-Prix - Race 1 results
| Cla | Driver | Team | Gap | Interval |
|---|---|---|---|---|
| 1 |  Pascal Wehrlein |
Porsche Team |
||
| 2 |  Jake Dennis |
 Andretti Autosport |
0.531 | 0.531 |
| 3 | Sam Bird |
Jaguar Racing |
3.526 | 2.995 |
| 4 |  Sébastien Buemi |
Envision Racing |
6.048 | 2.522 |
| 5 | René Rast |
McLaren |
7.471 | 1.423 |
| 6 |  Nick Cassidy |
Envision Racing |
7.614 | 0.143 |
| 7 |  Jean-Eric Vergne |
Dragon Racing |
12.394 | 4.780 |
| 8 | Jake Hughes |
McLaren |
15.187 | 2.793 |
| 9 | Andre Lotterer |
Andretti Autosport |
15.563 | 0.376 |
| 10 | Mitch Evans |
Jaguar Racing |
17.914 | 2.351 |
| 11 |  Stoffel Vandoorne |
Dragon Racing |
26.307 | 8.393 |
| 12 | Norman Nato |
 Nissan e.dams |
27.070 | 0.763 |
| 13 |  Lucas di Grassi |
 Mahindra Racing |
28.799 | 1.729 |
| 14 | Dan Ticktum |
NIO Formula E Team |
37.318 | 8.519 |
| 15 | Sergio Sette Camara |
NIO Formula E Team |
45.034 | 7.716 |
| 16 |  Kelvin van der Linde |
Team Abt |
1'00.135 | 15.101 |
| 17 | Sacha Fenestraz |
Nissan e.dams |
1'09.547 | 9.412 |
| 18 |  Antonio Felix da Costa |
Porsche Team |
1 Lap | 1 Lap |
| 19 | Oliver Rowland |
Mahindra Racing |
1 Lap | 16.067 |
| Edoardo Mortara |
 Maserati Racing |
7 Laps | 6 Laps | |
| Nico Müller |
Team Abt |
26 Laps | 19 Laps | |
| View full results | ||||
