Lorenzo fought his way past Dani Pedrosa with six laps to go to take his third win of the season and open a 20 point lead over Casey Stoner at the fifth round at Catalunya..
Monster Yamaha Tech3 rider Andrea Dovizioso was third, with Casey Stoner fourth and Brit rider Cal Crutchlow fifth.
Talking after the race Lorenzo told the press: "It was a very tough race. It was very hot and complicated. At the beginning it was very easy to touch Dani and end up on the ground, so I had to wait and be careful. Then Dani made one mistake which was enough for me to get through."
It's only my second time here and I shouldn't have let the leaders go at the start
Pedrosa got off to a flying start from fifth to lead into turn one as Stoner was pushed back to fifth from pole position.
Yamaha Factory Racing rider Ben Spies also got off to a great start and briefly took the lead on lap three but the American crashed out to leave Yamaha team-mate Lorenzo behind Pedrosa in second.
Spies rejoined and fought his way back through to finish 10th.
Lorenzo and Pedrosa swapped the lead twice before 2010 champion Lorenzo made the decisive move with six laps to go after Pedrosa wheelied.
Crutchlow and Stoner battled for most of the race with Crutchlow all over the back of Stoner in the closing laps but the Brit was fustrated by Stoners tactics and could not find a way past. Despite this Stoner finished off the podium for the first time in 20 races - a run stretching back to last April.
Crutchlow said: "It's only my second time here and I shouldn't have let the leaders go at the start.
"Then I ran wide and let Casey past and I just couldn't get past him. My team-mate [Dovizioso] was on the podium which shows what we can do but it will come around soon.
"It's Silverstone next and this sets us up for my home race."
•Jorge Lorenzo: 115 points
•Casey Stoner: 95 points
•Dani Pedrosa: 85 points
•Andrea Dovizioso: 60 points
•Cal Crutchlow: 56 points
•Valentino Rossi: 51 points
•Alvaro Bautista: 45 points
•Stefan Bradl: 43 points
•Nicky Hayden: 40 points
•Hector Barbera: 31 points