The Yamaha rider's maiden win of the season came in dramatic fashion at Motorland, as he took advantage of late crashes from the Repsol Honda duo of Marc Marquez and Dani Pedrosa.
With steady rain beginning to fall in Spain, the majority of the field opted to pit and change bikes to combat the slippery conditions.
However, with only a handful of laps remaining, both Marquez and Pedrosa chose to stay out on the circuit, and that gamble failed to pay off as both lost control with their tyres struggling for grip.
That left Lorenzo, who had pitted earlier to change his bike, able to cruise home to victory, ahead of Forward Yamaha's Aleix Espargaro and Cal Crutchlow of Ducati.
"Anything can happen and this sport is crazy sometimes," Lorenzo said. "It can surprise you in a positive or a negative way.
"This time for us it has been very, very positive because in these difficult conditions anything can happen and you have to be very focused, know when to change the bike and have a little bit of luck.
"Today we had a lot of luck, but also I rode very well in the dry and also the wet. I was very focused and gave everything to stay with Marc. So this victory is a combination of things.
"I thought, 'every lap is getting worse, we are going to crash sooner or later'.
"In the last corner I thought 'okay, do I want to stay with Marc or Dani or make the decision to pit'. I took a risk and entered the box. As I said we had some luck. I felt comfortable in the wet and today I took profit from my opportunity."
Lorenzo's team-mate Valentino Rossi crashed out in spectacular fashion early in the race and was taken to hospital for precautionary scans, while Pedrosa's 14th-place finish means Lorenzo has made up significant ground in the race for second place.
"In the last five or six races we've been on the podium," he said. "Japan last year was good for us and also we've been lucky on one side - unlucky for Valentino - that he crashed and also that Dani finished very far back today.
"So we've caught them a lot in the championship and it is a little more easy to fight for second place."