It was Lucas di Grassi, with only three points to his name so far this season, who pushed the Frenchman all the way to the line in an enthralling battle enjoyed by a capacity crowd.
The race got off to a messy start, as power issues for Nick Heidfeld left the Mahindra diver's car stricken at the side of the track.
The safety car was immediately deployed, though it seemed several drivers didn't get the memo as many continued to overtake as the cars began to bunch up on the track.
Though it was in keeping with the controversial theme which ran through qualifying in the Uruguayan coastal city.
Overall points leader Vergne was promoted to pole position after initial pacesetter Di Grassi was stripped of his lap time.
Di Grassi, along with DS Virgin Racing's Alex Lynn NIO driver Oliver Turvey, were each demoted a place after a lengthy investigation deemed the trio had hit a bollard on turn 15.
However, the disappointment of losing his first pole of the season appeared to fire Di Grassi up and it set up a thrilling battle between the pair as temperatures on the track peaked at 30 degrees.
But despite plenty of huffing and puffing from from the Brazilian driver, Vergne put in a masterclass of defensive driving to slam the door shut every time Di Grassi sniffed an opportunity to pass.
It's fair to say, however, that reigning world champion Di Grassi disagreed with the officials' decision to strip him of pole.
"I'm not really happy, they took away my pole position very unfairly," he told Channel 5 after the race. "And then on this track it is impossible to overtake.
"We had the fastest car but really it was going to be a crash or we stay as we are (first and second). Congratulations to Jean, he drove well.
"Today we had the fastest car for pole and to win but we came second."
The South American leg of the Formula E season has certainly been kind to Vergne, as he scooped his second first place finish on the continent after topping the podium in Santiago, Chile.
Despite the soaring temperatures on the Uruguayan coast, the Frenchman remained cool to also extend Techeetah's lead at the top of the team standings.
His victory, then, must be all the sweeter having fended off the challenge of Di Grassi, the man he calls "the best Formula E driver."
"Dealing with pressure is part of my life every day," he said matter-of-factly. "I'm glad the team is working so hard, sometimes it's not easy, sometimes I push them too hard, but they can see hard work pays off.
"It will make everyone in the team hungrier for success."
DS Virgin Racing driver Sam Bird completed the podium in third, though he appeared out of nowhere on the final two laps and looked for a fleeting moment like he might challenge the two race leaders who, it seemed, has become so engrossed in their own battle they had forgotten about the potential threat behind them.
However, it wasn't to be for the Brit but he will certainly take consolation from the fact he moved up seven places in the race to cement third place in the standings.
"Some good moves, staying clean, a great pit stop by the guys," Bird responded when asked how he caught the two leaders.
"I was able to get my head down and put in some laps and I could see the time coming down slowly.
"As I was catching, I was gaining energy as they were fighting, but I just didn't have the legs for the last couple of laps. Third from starting 10th is a good race."