Dowsett's time at Movistar saw him land time trial victory at Saltara on the 2013 Giro d'Italia and break the World Hour Record in May 2015, though opportunities to ride the Grand Tours were ultimately limited on the Spanish squad.
"It's so exciting for me to join this team. I had five amazing seasons with Movistar but it is time for a change and I look forward to joining Team Katusha Alpecin," Dowsett said.
"Every team has a different approach and I feel I can learn a lot. The nice thing for me is that I can stay on the phenomenal Canyon bikes. They were such a huge sponsor for me in the last years, and in my opinion, it's the best bike."
Katush-Alpecin has been active on the transfer market this summer, having already signed Marcel Kittel, Nathan Haas and Ian Boswell for the 2018 campaign as part of an extensive overhaul of its roster. Alexander Kristoff will leave Katusha for UAE-Emirates, but Tony Martin and Ilnur Zakarin both remain in situ in 2018.
While Dowsett will continue to place considerable emphasis on time trialling – he is a five-time British champion in the discipline – he will also enjoy something of a new role at Katusha as part of Kittel's lead-out train.
"I will continue to focus on my time trial but also all other races, especially stage races, including the Grand Tours, are important for me. I know that I will get my chances but I am ready to be a good domestique," Dowsett said. "In my period with Team Sky, I was one of the riders to protect Mark Cavendish and bring him to the last kilometer. I hope to do the same now with Marcel Kittel. I am good in positioning other riders in the sprint, but also on the climbs."
The arrival of the 28-year-old Dowsett was hailed by Katusha-Alpecin manager José Azevedo, who maintains that the Briton's skillset makes him a threat in short stage races. Dowsett won the Bayern Rundfahrt in 2015, a triumph built around his win in the time trial stage. The Briton, who turned professional in 2011 with Team Sky, has spent seven seasons at WorldTour level.
"Alex is one of the best time trial riders in the professional peloton. We see nice opportunities with him to bring horse power to the team in the team time trials," Azevedo said. "Moreover, because of his TT skills, he is able to win stage races, as he has proved already in the past. Alex is still young but he has a lot of experience. I have a good feeling about him."