Vinales, 22, mastered far-from-ideal conditions to finish ahead of Ducati's Andrea Dovizioso in second and Yamaha's fellow Italian Valentino Rossi, who was third, after rain had threatened to ruin the curtain-raiser under the Losail International Circuit's floodlights.
"It feels great," Vinales told www.crash.net after the race. "The track was so difficult. I was taking so much care at the start.
"Anyway, the bike was great. I have to say thanks to the team. Even if the conditions were difficult we were there all the time. I'm so pleased to be with Yamaha."
Reigning champion Marc Marquez had to settle for fourth as Vinales, who started on pole position, became the first rider to win on his debut for a new team since Casey Stoner (Repsol Honda) in 2011.
Qatar MotoGP Results & Championship Standings
Race Result
1 Maverick Vinales (Spa) Yamaha 38mins 59.999secs
2 Andrea Dovizioso (Ita) Ducati 39:00.460
3 Valentino Rossi (Ita) Yamaha 39:01.927
4 Marc Marquez (Spa) Honda 39:06.744
5 Dani Pedrosa (Spa) Honda 39:07.127
6 Aleix Espargaro (Spa) Aprilia 39:07.660
7 Scott Redding (Gbr) Ducati 39:09.781
8 Jack Miller (Aus) Honda 39:14.485
9 Alex Rins (Spa) Suzuki 39:14.787
10 Jonas Folger (Ger) Yamaha 39:15.068
Rider Standings
1 Maverick Vinales (Spa) Yamaha 25pts
2 Andrea Dovizioso (Ita) Ducati 20
3 Valentino Rossi (Ita) Yamaha 16
4 Marc Marquez (Spa) Honda 13
5 Dani Pedrosa (Spa) Honda 11
6 Aleix Espargaro (Spa) Aprilia 10
7 Scott Redding (Gbr) Ducati 9
8 Jack Miller (Aus) Honda 8
9 Alex Rins (Spa) Suzuki 7
10 Jonas Folger (Ger) Yamaha 6
Manufacturers Standings
1 Yamaha 25pts
2 Ducati 20
3 Honda 13
4 Aprilia 10
5 Suzuki 7