The German managed to finish second, ahead of Ferrari's Fernando Alonso in third place.
You can read how Rosberg took the second pole of his career below.
Good afternoon. Welcome to Sports Mole for live coverage of the qualifying session for the Bahrain Grand Prix.
Q1 is underway and Fernando Alonso is on top of the standings. Charles Pic, Jules Bianchi, Max Chilton and Giemo van der Garde are all in the knockout zone.
Daniel Ricciardo and Pastor Maldonado have also joined those drivers currently in the drop zone. Lewis Hamilton has already received a five-place grid penalty for a change of gearbox.
Time is up for Q1. Alonso is on top, with Vettel, Rosberg, Grosjean, Hamilton, Di Resta, Massa, Raikkonen, Webber and Sutil completing the top 10.
DRIVERS KNOCKED OUT: Maldonado, Gutierrez, Pic, Bianchi, Van der Garde, Chilton.
It has not been a great session for Pastor Maldonado, who exits Q1 yet again. We're about to get the green light for Q2, so who will be in the top-10 shootout?
Mark Webber is the first man out of the trap for Q2 on the medium compound tyres. He is followed by his teammate Sebastian Vettel.
The Marussia garage have got the fire extinguishers out for Jules Bianchi's car. The cause isn't clear at the moment, but the same car has a fuel vapour fire this morning, so there's a few problems there it seems.
Vettel was the fastest of the early starters, but Di Resta has just set a rapid lap to go top. Those two are followed by Webber, Raikkonen, Sutil, Hulkenberg, Ricciardo and Vergne.
Alonso has now set the quickest lap with just over six minutes of Q2 remaining. Ricciardo, Bottas and Vergne are currently in the danger zone.
There was nearly a coming together there between Hulkenberg and Massa. The Ferrari just dawdled slightly as the German was making his way through. I'm sure the stewards will have a look at that one.
Rosberg shaves 0.449 of a second off Alonso's time at the top. Brilliant lap.
Just over two minutes left now. Button, Perez, Hulkenberg, Ricciardo, Bottas and Vergne the slowest at the moment.
The top four, Rosberg, Alonso, Di Resta and Hamilton, are all in the garage, seemingly content that they'll be in Q3.
Button has one lap now to get into Q3. He and his McLaren teammate Sergio Perez are struggling in the knockout zone.
Sutil's final lap is good enough for a place in the top-10 shootout, as is Button's. However, Perez has been unable to get out of the knockout zone and drops out. His disappointing season continues here in Bahrain.
DRIVERS KNOCKED OUT: Grosjean, Perez, Ricciardo, Hulkenberg, Bottas, Vergne.
Vettel, Rosberg, Webber, Raikkonen, Alonso, Di Resta, Hamilton, Massa Sutil and Button will contest the top-10 shootout.
Button was heard celebrating on team radio after scraping through into Q3. It's a sign of the struggles McLaren have had at the start of this season.
The lights go green for the start of Q3. The cars are straight out, headed by Paul di Resta.
There's still six cars yet to come out and set a time. Those out early are also back in the garage now. Slightly similar circumstances to last week, where the drivers were trying to save their tyres.
Of those that came out, Rosberg was the fastest. Alonso, Hamilotn and Di Resta came next. The Force India was quite a bit off the pace, though.
All 10 cars are now on the track with over one minute remaining.
The chequered flag is out. Rosberg is the one on top, followed by Alonso, Hamilton and Webber.
NICO ROSBERG WILL START ON POLE FOR THE BAHRAIN GRAND PRIX
Great effort from the German! Vettel could only manage second, while Alonso ended up third. So Mercedes and Red Bull will start on the front of the grid, with Ferrari third.
TOP 10: Rosberg, Vettel, Alonso, Hamilton, Webber, Massa, Di Resta, Sutil, Raikkonen, Button.
Of course, factor into that that Hamilton has a five-place grid penalty. So he will start in between Raikkonen and Button. Webber will also be demoted three places, which puts him in between Sutil and Raikkonen.
Well that's the end of the qualifying session for the Bahrain Grand Prix, which brings our coverage to an end for today. Thanks for stopping by, and come back tomorrow for what is always an exciting race.