"The cold helped us here", Hamilton admitted after winning in China.
It was also a great day for Red Bull's Max Verstappen, who clawed his way up to a podium position from 16th place on the starting grid.
Hamilton is predicting an epic battle for the title after a captivating start.
Vettel's race was scuppered by a sheer bad luck.
Lance Stroll, the 18-year-old rookie, spun off the track on the first lap after making contact with Force India's Sergio Perez.
That left Vettel in a strong position to take the lead when Hamilton did pit, but he was saved by Giovinazzi stacking his auto leading to a safety vehicle, which allowed Hamilton to pit for his tyres - and win the race.
Hamilton leads from pole to claim his fifth win in Shanghai, his first of the new season.
Hamilton, who finished second to Vettel in Melbourne, heads into the next race in Bahrain in a week's time tied on points with the German.
The battle for the victory at the close was very much a two-horse race beetween Hamilton and Vettel; however, with the Briton coming out ahead of the German, having taken pole into the race.
Speaking alongside Verstappen at the post-race press conference, Hamilton said: "I quite like him up here it makes me look younger while I'm up here, it's good to have a younger person around".
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"The ultimate fighter always wants to go up against the best battle you can have".
World Health Organization is most likely to win the 2017 Formula One Drivers' Championship, according to the odds? All the drivers made quick exits from the garage to allow ample time to test their full array of tires before qualifying later in the day.
Marchionne expressed some frustration with the failure of Raikkonen to get past Daniel Ricciardo in the early stages of the race, at a time when Vettel was also behind him.
So it seemed a reasonable forecast that Vettel would be quicker and more wily and take a second win for Ferrari.
Leading lights: Race victor Lewis Hamilton with second placed Sebastian Vettel (left) and third placed Max Verstappen.
It proved the right decision as the track dried out and those ahead of him were forced to change tyres on lap four, with Vettel now back in sixth. "Lewis did the best job", said Vettel.
"The safety auto came just when I was about to start to feel that the dry tyre was a lot quicker, Vettel said". I am very happy to be on the podium.
The Chinese GP went a long way toward proving that F1's new rules and regulations won't hamper the competition and entertainment that fans expect from Formula One.
"He appears to have an nearly sixth sense in the wet".