Vettel and teammate Kimi Raikkonen had been unable to challenge Hamilton in Melbourne qualifying, both finishing almost seven tenths off the reigning champion.
But a different strategy coupled with a fortuitously-timed virtual safety car interruption in the race allowed the German to jump from third to first in the order, and he duly held off Hamilton for victory.
Vettel conceded after the race that he was "a bit lucky" to win, as he admitted Ferrari was not yet where it wanted to be.
"If you look at the gaps the whole weekend, we are not yet a true match [for Mercedes]," he conceded.
"Therefore at this point we know that we are not yet where we want to be, because we want to be fastest."
The 2018 Australian GP echoed last year's F1 season opener at the same venue, in which Vettel lik