The 39-year-old Welshman, who conquered cycling's biggest stages from Olympic velodromes to the 2018 Tour de France, had announced earlier in 2025 that this would be his last year in the peloton and could not have scripted a more perfect farewell.
Fittingly, the final stage began at the velodrome named after Thomas, while it also ran within 100 metres of his parents' home, his childhood cycling club Maindy Flyers and - as the Welshman described - the pub where he had his first pint.
As he crossed the finish line in Cardiff, Thomas got visibly emotional as he was congratulated by his teammates.
"I was emotional crossing the line. I was riding through Birch Grove and all the fans, it was just like, almost like choking up riding my bike, which was weird," Thomas said.
"It's definitely emotional, super special though. I've been saying since the route was announced that to finish here, it's just unbelievable.
"And the fans, it's just like the support I've had over the years, it's incredible. So to finish here, it's like full circle, right past Maindy ... where it all started. There's no better way."
Thomas received a guard of honour before the stage began in Newport, with fellow riders propping up their bikes amid applause from fans who braved wet weather to witness their Welsh hero's final ride.
His remarkable transformation from a rider who finished his first Tour de France in penultimate position to proudly wearing the yellow jersey on the Champs-Elysees 11 years later exemplified his extraordinary journey.
Thomas helped his team, previously known as Team Sky, claim seven Tours de France.
He supported Chris Froome's four victories and Bradley Wiggins' triumph before claiming his own slice of history as the first Welshman to win cycling's greatest prize and coming second to Egan Bernal the following year when they became Team INEOS.
With no more training or racing on the horizon, Thomas said he wanted to "switch off for a bit" and spend time with his family.
"I'll go back, go take this lad (his son) to school on Tuesday, so back to normality," he said. "Really do stuff that I don't really ever get to do, so it'll be nice."