Thomas becomes only the third Brit to achieve such a feat and he follows in the footsteps of fellow Team Sky stars Chris Froome and Sir Bradley Wiggins.
Team Sky, who have won six of the last seven competitions across the England channel, allowed French veteran Sylvain Chavanel, 39, to temporarily lead race onto the Champs-Elysees, 60km from the end.
The British cycling stronghold were relaxed during the final stage and often posed for pictures alongside their team vehicle, once Froome had caught them up that was.
Joyously, the team sipped champagne while cruising to the finish line, a moment to be enjoyed and cherished after a fortnight of hard work.
Thomas had put himself in the driving seat during Stage 11 and he strengthened his grip significantly when he became the first ever British winner at the Alpe d’Huez.
And the 32-year-old struggled to contain his excitement after crossing the finishing line for one final time.
“When I rode the Champs Elysees for the first time in 2007 that was insane just to finish the race and just to be a part of it,” he said.
“To now to be riding round winning it is just incredible. It won’t really sink in for a few months, it’s just a whirlwind now.
“I seem to be floating around on cloud nine.
“Maybe when I’m like 70 sat in a corner of a pub telling some 18-year-old what I used to be it’ll sink it. It’s incredible, the stuff of dreams.”
Team Sunweb’s Tom Dumoulin finished second but he was some one minute and 51 seconds behind the winner.
Froome completed the top three almost two and a half minutes behind his team-mate.
But Alexander Kristoff (UAE Team Emirates) came out of nowhere to steal a memorable Stage 21 win in a dramatic final sprint, with John Degenkolb second and Arnaud Demare third.
Speaking after winning the final stage, Kristoff said: “That’s a dream coming true, I’ve been close before but never managed to beat the faster guys like Mark Cavendish, Marcel Kittel and Andre Greipel.
“They are not here today, they are out after the mountains and I managed to win.
“I was a bit far back but I was with my team-mate Roberto Ferrari and I managed to move up and pass John Degenkolb.
“It was still far out but no one was able to close on me and in the last 20m, I knew I would win.”
Final general classification
Geraint Thomas (GB/Team Sky) 83hrs 17mins 13secs
Tom Dumoulin (Ned/Team Sunweb) +1min 51secs
Chris Froome (GB/Team Sky) +2mins 24secs
Primoz Roglic (Slo/Team LottoNL-Jumbo) +3mins 22secs
Steven Kruijswijk (Ned/Lotto NL-Jumbo) +6mins 08secs
Romain Bardet (Fra/AG2R La Mondiale) +6mins 57secs
Mikel Landa (Spa/Movistar) +7mins 37secs
Daniel Martin (Ire/UAE Team Emirates) +9mins 05secs
Ilnur Zakarin (Rus/Katusha-Alpecin) +12mins 37secs
Nairo Quintana (Col/Movistar Team) +14mins 18secs