Mir had work to do after he only qualified in 12th, but Fabio Quartararo – second heading into the race - crashed out allowing the Suzuki star to get the job done with minimal pressure.
He was never a threat to Morbidelli at the front, with the Italian claiming his third victory of the season, but Mir's conservative ride after Quartararo's exit did the job.
It sealed Suzuki Ecstar’s first championship since 2000 and Mir completed it with a race to spare, with Portimao up next weekend.
While it would have taken a remarkable turn of events to prevent Mir taking the title eventually, Quartararo crashing out with 19 laps to go meant it was more or less game over, ending the Frenchman's hopes of catching the Spaniard on the leaderboard.
That left Morbidelli in the driving seat at the front and he was in commanding form for the most part, though he was certainly forced into a fight at the end with Jack Miller on his tail.
Mir was not in contention for the podium finish that would have guaranteed him the title, spending much of the race seventh.
Having won only his first MotoGP™ race a week earlier, Mir cemented his name in the record books as he saw out his championship victory in a professional manner.
- Franco Morbidelli (Petronas Yamaha)
- Jack Miller (Pramac Racing) +0.093
- Pol Espargaro (Red Bull KTM) +3.006
- Alex Rins (Suzuki Ecstar) +3.697
- Brad Binder (Red Bull KTM) +4.127
- Miguel Oliveira (Tech 3 KTM) +7.272
- Joan Mir (Suzuki Ecstar) +8.703
- Andrea Dovizioso (Ducati) +8.729
- Aleix Espargaro (Aprilia) +15.512
- Maverick Vinales (Monster Energy Yamaha) +19.043
- Joan Mir (Suzuki Ecstar) 171
- Franco Morbidelli (Petronas Yamaha) 142
- Alex Rins (Suzuki Ecstar) 138
- Maverick Vinales (Monster Energy Yamaha) 127
- Fabio Quartararo (Petronas Yamaha) 125
- Suzuki Ecstar 309
- Petronas Yamaha 230
- Red Bull KTM 209
- Ducati 194
- Monster Energy Yamaha 169
MotoGP™ heads to Portugal and Portimao for its season finale next weekend, with Mir looking to end his victorious campaign on a high and the rest of the pack hoping to seal one final slice of glory.