The 23-year-old won the opening stage of the Tour de Yorkshire and took the first leader's jersey in May, having finished second in the Commonwealth Games time trial on the Gold Coast, Australia, to Cameron Meyer while riding for Team England the month before.
He subsequently finished second at the British national championships time trial in June behind Team Sky's Geraint Thomas, who would go on to win this year's Tour de France. If his successful season to date has already been hard for the man from North Yorkshire to believe, signing for Katusha-Alpecin is the cherry on the cake.
"The WorldTour has always been the ultimate ambition," Tanfield said in a press release. "I have a foot in the door now, and have two years to prove myself. I don't pretend to think I have made it. The hard work starts now and the challenge is for me to show I can progress as a rider."
Katusha-Alpecin general manager José Azevedo is thrilled to be welcoming Tanfield to the team, where he will join fellow British rider Alex Dowsett.
"We've been watching Harry with our [bike supplier] partner Canyon for a while," Azevedo said. "He's not only a talented time trial rider. We have seen on this year's Tour de Yorkshire that he has all the skills to win big races. While this is a big step for him now, we as a team will provide him with the best possible support to continue his positive development."
Canyon Eisberg directeur sportif Tim Elverson is equally thrilled that the UCI Continental team has been able to produce a rider of Tanfield's calibre.
"I'm super happy," Elverson said. "It's great that Harry's work has been recognised, because he really does deserve it. It underlines Canyon's commitment to our relationship, and also shows we are operating at a level where we can deliver someone to the WorldTour.
"Katusha-Alpecin are getting a very strong, young rider. Hopefully they can help him progress to the next stage, and that is to be a reliable WorldTour rider. I have no doubt that is what Harry will become. And from everyone at Canyon Eisberg, we wish him the very best of luck."
Tanfield added: "I wanted to honour the faith Canyon has put in me through Tim and Nick Allen [Canyon UK], so joining Katusha-Alpecin was always the dream. I had just set out on a training ride when José rang me. I was over the moon. Now I just can't wait to get started. I have to thank everyone at Canyon Eisberg, but especially Tim. We've worked together for three years and it has been a great ride."