The two Welshmen will join former world champion Michal Kwiatkowski in the line-up, with three more riders still to be confirmed to complete the six-strong team.
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The Tour of Britain will be Thomas’s first race back since breaking his collarbone in a crash at the Tour de France in July, while Doull will be making his first appearance in his home tour since finishing third overall and winning the points classification while riding for Team Wiggins.
“It’s always great to be able to race in front of home fans, so I’m really looking forward to the Tour of Britain,” Thomas said.
Watch: Tour of Britain essential guide
“I haven’t had the chance to race at home much in recent years, but the atmosphere at London 2012, then at the home stages of the Tour de France and Commonwealth Games in 2014, has always stayed with me.
“The support from British fans is always fantastic when we race abroad – especially from the Welsh fans! There aren’t many races now where I don’t see the flag at the side of the road, and it just gives you such a boost.”
Team Sky will be heading to the race hoping to take overall victory for the first time since Bradley Wiggins won yellow in the 2013 edition.
The race starts in Edinburgh on September 3, and features a flatter parcours than in previous years, with the majority of stages being suited to the sprinter and a time trial in Essex that will likely decide the general classification.