The Welshman won the Tour in July after gold medals in the Olympics and a Classics career. He wants to continue the journey in his home team, signing a deal that could likely see him ride out his carrier in Sky colours.
"It's been a great journey for me with Team Sky and obviously the last few months have been crazy," Thomas said.
"It's working really well for me here and I'm excited about what's still to come."
Thomas, 32, joined from Barloworld when Sky debuted in the 2010 season. First he rode by the side of Bradley Wiggins and then Chris Froome. This year, he had his chance to win the Tour.
Last summer, the team confirmed Froome through the 2020 season. Froome then went on to win a fourth Tour title and the Vuelta a España in 2017, and the 2018 Giro d'Italia.
Froome now wants to aim for a fifth Tour in 2019 and a shot at equalling the record of five victories. Also, Sky have emerging talent Colombian Egan Bernal on their roster.
It is crowded at times with so many stars, but the family feel means too much to Thomas.
"It really is one big happy family where my relationship with Team Sky is concerned, so I couldn't be more delighted," he continued.
"I feel at home with the Team. I've known Dave [Brailsford], Rod [Ellingworth] and Fran [Millar] for years, since I was 17, so it's great that I'll be continuing to work alongside those guys and the rest of the Team."
Thomas will need to find his space alongside Froome and future stars like Bernal, but he has had it so far. Sky will pay to keep him, though. Thomas could have inked the biggest contract of his career at an estimated £3.5 million ($4.6m).
Froome's salary is an unknown, but estimates have it around £4 million. It's a lot to keep them both in the roster, but Team Sky runs on the largest budget in the WorldTour at a reported £31 million annual budget.
"What Geraint has achieved with this team is nothing short of remarkable. It's a brilliant story," Team Sky Manager Dave Brailsford said.
"He's made sacrifices to get to the top of the sport – and it's all proved to be worth it.
"Winning the Dauphiné earlier this year gave him the belief and determination that he could win the Tour de France and it's all credit to him. He just keeps on improving through commitment and hard work and now he's at the very top table as a Tour de France winner.
"He's achieved his dream of winning the Tour, but there's so much more ahead for him."
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