The 28-year-old Manxman was one of Team Sky's original panel of six riders when he turned professional with them in 2010 but was left out of this year's Tour de France squad.
Kennaugh played supporting roles in Chris Froome's Tour victories in 2013 and 2015, is a two-time national road champion and took stages at last year's Vuelta a Espana and last month's Criterium du Dauphine.
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He will now link up with world champion Peter Sagan at Bora and is looking forward to opening a new chapter.
"I wanted a change, some new motivation and a different experience," he told Cyclingnews.
"I don't think I was getting stale at Team Sky but a fresh way of doing things will just keep me fresh. Maybe part of me felt that I was getting too relaxed. It's exciting times."
"I guess with the Tour going down to eight riders next year it's going to be hard to get into any team. Bora are a top team too so it's going to be a fight to make that squad too but that will just keep me on my toes."
Tour de France
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