Practice had suggested that Mercedes would be able to give Red Bull a much harder time in qualifying at least at Yeongam.
That lap had put Hamilton in third behind the second Red Bull of Mark Webber.
Although Hamilton was able to get ahead of the Australian on his final pole shot, he was still 0.218s adrift of Vettel, who was able to back off his own last lap, confident pole was secure.
Webber also abandoned his final lap and stayed third in the times, which will become 13th on the grid when his 10-place grid penalty for accumulating three driving reprimands is applied.
Grosjean's team-mate Kimi Raikkonen could only manage 10th, 1.3s slower.
Sauber's qualifying breakthrough came at McLaren's expense.
Despite encouraging signs in practice, the silver cars found themselves back in 11th and 12th, with Sergio Perez and Jenson Button missing Q3 by just 0.035s and 0.038s respectively.
The Toro Rossos and Force Indias were also eliminated in Q2, while neither Williams made it beyond Q1, although Valtteri Bottas could at least be pleased to outqualify Pastor Maldonado by half a second.
Charles Pic squeezed ahead of Caterham team-mate Giedo van der Garde by 0.007s to lead the rear quartet.