Hamilton is now 28 points ahead of his Mercedes team-mate with eight races remaining after his first win at this most historic of races in five years.
Holding off the challenge from the Force India of Sergio Perez on the run down to Les Combes – the scene of his collision with Rosberg here last year – pole-sitter Hamilton never looked back, and from there he made it look easy as Rosberg was forced to settle for second.
Hamilton left this race last year trailing Rosberg by 29 points and still went on to win the title. Last night he left the iconic Spa-Francorchamps with clear daylight between him and the German.
But the 30-year-old warned it is not a forgone conclusion he will become the first British driver to successfully defend his F1 crown.
“It is definitely way too early for that,” Hamilton said, following his sixth victory of the season and the 39th of his career.
“You want to get those pole positions and translate them into wins and hopefully today is the beginning of that, so I am looking forward to the next races.
“Nico had good pace but I was able to answer most of the time, so I was fairly relaxed at the front.”
Upon F1’s return to action after a four-week summer break, much had been made of the new start procedures.
The responsibility was being placed back in the hands of drivers – as opposed to the boffins sitting on the pit wall – and the premise was that it would lead to unpredictable starts and more dynamic racing.
And of the two Mercedes men sitting on the front row, it was Hamilton who after a hat-trick of sluggish starts, appeared to revel in the new directive.
In contrast, Rosberg was gobbled up on the run down to turn one to leave him in fifth. It was always going to be an uphill struggle from there.
“The start was really bad so I need to practice that,” said Rosberg who recovered to finish second with Romain Grosjean benefiting from Sebastian Vettel’s late puncture to take the final spot on the podium. “I was trying to hunt Lewis down but he did a great job and it wasn’t enough.”
Perez, who started from fourth, was quickest out of the blocks in his Force India. He drew alongside Hamilton on the run down to Les Combes but the Mercedes man held the inside line and held off the challenge from the Mexican.
Daniel Ricciardo, winner here last season, was up to third in his Red Bull. The Williams of Valtteri Bottas was ahead of Rosberg, but it did not last for long. Rosberg, set to become a father for the first time next week, made his move on the Finnish driver at the chicane towards the end of lap one to take fourth.
Hamilton then laid down the gauntlet to his rivals at the sharp end of the pack with a number of impressive laps. By the end of lap four he had moved clear of Perez and was already five ahead of Rosberg. From there the race, which saw none of the rain which had been forecast, was all but over.
Ricciardo was the first of the leading pack to pit at the end of lap six. Perez promptly followed which promoted Rosberg up to second, almost nine seconds behind his championship rival.
Rosberg made his first stop at the end of lap 11 and his superior pace saw him rejoin the track ahead of Perez for a net second place. Perez, in his Mercedes-powered Force India, drew alongside Rosberg on the Kemmel Straight, but just as his team-mate did on the opening lap, the German held position.
Hamilton stopped for a change to the prime tyre on the following lap. He retained the lead, but lost the best part of five seconds to his team-mate. Rosberg now trailed the leader by a little over three seconds. Ricciardo’s race then came to an abrupt end as he stopped with a mechanical issue on the pit straight.
The virtual safety car was deployed to slow the field down, but when it was withdrawn a little over two laps later, Rosberg had slashed the gap to Hamilton from a little over three seconds to nearer two. “Nico is definitely closer than when the VSC came out,” Hamilton observed over the team radio. He had a point, but it did not matter. Rosberg was unable to get any closer, and for Hamilton, it was yet another regulation win.
Elsewhere, Williams were left embarrassed when they fitted three option tyres and one prime tyre on Bottas’ car. The different tyre compounds are defined by yellow, for option, and white for the prime. He was hit with a drive-through penalty and his race scuppered.
Retaining the comical theme, Jenson Button suggested that McLaren had “forgotten to connect the batteries”. Down on power, he limped home in 14th ahead of only the Manor duo of Roberto Merhi and Will Stevens. Fernando Alonso was just one place better off on another sour day for McLaren.
Grosjean, who qualified fourth but was demoted to ninth after a gearbox change, then took the final spot on the podium after Vettel’s puncture. The four-time world champion, in his 150th race and who won last time out in Hungary, finished outside of the points.
Behind Grosjean, Daniil Kvyat was fourth for Red Bull, Perez fifth and Felipe Massa sixth for Williams. Kimi Raikkonen crossed the line in seventh for Ferrari with Max Verstappen, Bottas, and Sauber driver Marcus Ericsson rounding out the top ten.