The 28-year-old Briton led from pole position to the chequered flag, apart from three short spells for pit-stops, as he secured his fourth victory at the Hungaroring in sweltering conditions.
The 2008 champion came home 11 seconds clear of Kimi Raikkonen of Lotus and third-placed defending triple world champion Sebastien Vettel of Red Bull, who was unable to force his way into second place in the closing laps.
It was Hamilton's 22nd win of his career and a success that restored him among the challengers for this year's drivers' championship.
"It's an incredible feeling and I'd like to thank all the fans here," said Hamilton. "My team did an incredible job, we studied a lot last night and were hoping the tyres would last.
"We had no idea it would go that well, but I was hungry for it today. I was going all out. Usually, I get stuck in traffic, but today I was going for every move I could. I wasn't having any of that..." "This has been one of the best and most important wins of my career," he added.