The 22-year-old, who has raced for Team Wiggins the past two years, won the U23 time trial title at the national championships for the past four years running, and finished in the top 10 in the U23 time trial at the recent World Championships.
"I'm delighted to be joining Team Dimension Data for Qhubeka next season. It's a dream come true for me to be joining a WorldTour team with such a great cause," said Davies.
"I'm grateful to Team Wiggins for their support over the last couple of seasons, and for giving me so many opportunities to develop myself. I'm now ready to continue my development and start a new and exciting chapter with Dimension Data for Qhubeka."
Davies won the Junior Tour of Wales in 2013 and earned a ride with Madison-Genesis in 2014, before joining the team set up by Bradley Wiggins in 2016. That year, he won a stage and finished ninth overall at the Ronde de l'Isard and placed second at the Tour Alsace. This year, as well as landing the national time trial title and a Worlds top 10, he finished fourth overall at the U23 Giro d'Italia.
The Dimension Data team labeled him "a real talent for the future" as they unveiled his signing on Thursday.
Davies will join fellow Brits Mark Cavendish, Steve Cummings and Scott Thwaites at Dimension Data, while he's the third British rider to turn pro at WorldTour level in 2018, along with Chris Lawless (Team Sky) and James Knox (Quick-Step Floors).
Anton extends for another year
The team also announced that Spanish veteran Igor Anton has extended his contract by another year, which will see him through to the end of the 2018 season.
The 34-year-old, who spent most of his career at the Basque Euskaltel-Euskadi squad, joined from Movistar in 2016 and has ridden both the Giro d'Italia and Vuelta a España in the past two seasons. Anton will provide support in the mountains to the team's general classification leader, Louis Meintjes, who is returning to the team after a spell at UAE Team Emirates, but there will also be stage races where the Spaniard can race for his own results.
"I am really happy and feel very fortunate to stay in the professional peloton for another year. I want to thank the team for this opportunity to stay in the sport I love so much," Anton said.
"At the Vuelta this year I could see I was not so far off the top level and it convinced me I still have more to give. Whether I ride for a result or support the young guys like Louis Meintjes or Ben O'Connor, I am motivated to give my all for this very unique and special team. I think we have a very nice bond in the team and I am happy I will be able to remain in this environment."