It was Hamilton’s fourth successive win, and the team’s fourth consecutive one-two.
This race, however, is likely to be one that will hurt Rosberg for some time ahead of Formula One’s blue riband event in Monaco in a fortnight.
Although Hamilton was clean away from pole, the 29-year-old grumbled often throughout the race, complaining about oversteer, the back end of the car sliding out, graining on his tyres, his strategy, and how much time he had lost to Rosberg in the pit stops.
At times it was a nervous, tetchy Hamilton behind the wheel, whereas Rosberg appeared to drive serenely behind as he managed the gap to his championship rival. To give the German his shot at victory, Mercedes altered tyre plans from the first stop onwards, and as the race reached its denouement, Rosberg reeled Hamilton in.
But despite finally managing to get within a second late on, Rosberg ran out of laps and not once had a crack at making a pass on Hamilton, who ultimately won by just 0.6 seconds.
For the first time since June 2012, Hamilton now leads the drivers’ standings, moving three points ahead of Rosberg, who must be wondering what he has to do to triumph again.
As wins go, Hamilton’s first in Spain, this one was crucial: “It means everything to me.
“Getting my first grand prix win here after being in the sport eight years, it’s very difficult to put the feeling into words. Never have I had a car like this, nor a gap like this to anyone before.
“But I know I wasn’t fast enough. Nico was quicker, I struggled with the balance, but fortunately I was able to keep him behind.”
Despite the rivalry between the duo — there was undoubted tension in the green room before they went on the podium as barely a word was exchanged between them — Hamilton insists they can remain friends.
“We’ve been racing together for a long time, so I don’t see why not,” remarked Hamilton.
Rosberg is determined Hamilton will not make it five wins in a row in Monaco, a race the German won from pole last year.
“Second place, I’m still close in the championship and with many more races to go,” said Rosberg.
“I’ll put in a massive effort to go one better, to repeat the win from last year.”
Mercedes’ dominance was such that Daniel Ricciardo finished 49 seconds adrift in his Red Bull.
As for Ricciardo’s team-mate Sebastian Vettel, the reigning four-times champion conjured his best drive of the season finishing fourth after starting 15th.
Williams’ Valtteri Bottas was fifth, whilst Ferrari, winners here last year with Fernando Alonso, had to settle for sixth and seventh, with Kimi Raikkonen passed by the Spaniard two laps from home.