The reigning world champion took control of what proved to be a chaotic 45-lap race at times, with several drivers coming to grief on the tight 1.8-kilometer track around the Central Harborfront.
Buemi, who clinched the 2016-16 title at July's season-ending
London ePrix, started from fifth on the grid for the Renault e.dams team but profited from crashes to his immediate rivals.
Early casualties included pole sitter Nelson Piquet Jr., who races for the NextEV team, and DS Virgin Racing's new driver Jose Maria Lopez, who qualified third.
And when Lopez's teammate Sam Bird suffered mechanical difficulties during his pit stop to change cars, the road cleared for Buemi.
The Swiss took charge but was chased all the way to the line by rival Lucas di Grassi -- the ABT Schaeffler driver made remarkable progress to eventually finish second after starting the race down in 19th place.
Nick Heidfeld made up the podium places for Indian team Mahindra.
"It was a great first race and a great start to the season," Buemi said at the post-race press conference.
"When you see so many people it's just an amazing feeling. The track was good -- maybe a little bit short. But it's a great start I'm looking forward to coming back."
There was little luck for the new teams -- China's Techeetah had an unhappy first race, with both Ma Qing Hua and teammate Jean-Eric Vergne forced to retire.
Jaguar fared a little better in its return to competitive motorsport -- Mitch Evans bowed out after 24 laps but Adam Carroll came home a creditable 12th.
Umbrellas were expected to be essential for race day -- rain was forecast over the weekend -- but in the end they were only unfurled to shelter from blazing sunshine for the most part.
Race promoter Alan Fang estimated around 25,000 spectators came through the turnstiles over the two-day event.
"It's something we're very proud of. Did we do everything perfectly? Probably not," said Fang, who is the CEO of Formula Electric Racing Limited.
"It's the first time and I think we gave it a good shot. And it's something we'd like to improve when we do it again."
Ticket prices was an issue that was raised by a number of people CNN spoke to outside the venue -- a seat in the grandstands flanking the start/finish straight cost HKD2,380 ($300) for the weekend, with two-day entry to the eVillage costing HKD300 ($40).
"We've tried to build the eVillage to make it more family orientated -- entertainment, music, people having a good time," Fang told CNN.
"For HKD300 for two days we think it's actually quite reasonable. The grandstands -- HKD2,380 is a price we think is reasonable enough and it was sold out prior to the event.
"It's quite expensive to put on a race ... it's about a balance -- offering enough people to come to the eVillage to enjoy themselves.
"In the end the more revenue there is, the better we can make the race."
Drivers' thumbs up
Consensus among the drivers was that the circuit was a little narrow. "We have to look to next year, make it a little bit better, a little wider," di Grassi said.
But the Brazilian praised the atmosphere in Hong Kong.
"What I enjoyed especially ... I got the feeling that there were more people (watching)," he said -- a sentiment echoed by fellow former F1 driver Heidfeld.
"It was a bit like Formula One when I was in Montreal (at the Canadian Grand Prix)," said the German driver, who spent 12 seasons in motorsport's premier racing series.
"The whole city lifted and it was amazing."
The Hong Kong race is the first of 12 in the 2016-17 all-electric world championship, with New York and Montreal also slated to host events.
Teams and drivers head to Morocco next -- Marrakesh will hold its first Formula E race on November 12.