The Canadian currently rides for Cannonade-Garmin and the move brings to an end an eight-year association with the Garmin half of that merger, where he has ridden since its inception in 2008.
The highlight of Hesjedal's career came when he won the 2012 Giro d'Italia and he was fifth in this year's edition of the race before riding to third on the final mountain stage of the Tour de France to l'Alpe d'Huez. The 34-year-old will now join forces with Bauke Mollema as part of Trek's GC ambitions, with a particular focus on next year's Giro.
"I have excellent memories from the past seasons and I have a lot of friends there. But I’m thrilled about this change of air. I believe it’s what I needed," said Hesjedal in a team statement.
"I am very excited about this. Trek’s management and I are on the same page in terms of what we can achieve together. I know that I still have podium level legs for the Grand Tours. People ask me if I’m contemplating the end of my career. If I was, the circle would now be complete," he added, referring to the fact he began his professional career riding a Trek bicycle for US Postal in 2004.
"The truth is I don’t really know how long I’ll still be racing. As far as performance goes, and how I feel, I feel there’s still a lot in there. This year’s Giro was a confirmation of that. But yes, I don’t see myself racing for another five years. One, two or three, we’ll see."
Hesjedal's priority will be to try and repeat his Giro triumph of 2012 but he will also target the Ardennes Classics as preparation. The Canadian has a string of top-10 finishes to his name in those races, including second at Amstel Gold in 2010.
"The Ardennes Classics will be important as well," he said. "You basically work backwards with the Giro being the number one goal. The rhythm to get to your best shape in the Giro leads you to those races. I know the routine to get there."
The signing was announced by Trek Factory Racing in a slightly unorthodox but thoroughly modern manner, via a series of cryptic clues on Twitter, as set out below.
The team confirmed the signing to Cyclingnews and later sent out a more traditional press release. In it the team's general manager Luca Guercilena expressed his delight at securing Hesjedal's signature.
"This is an excellent signing for our team and I have no doubt our fans in North America will be very happy as well. Ryder is a very strong racer and he has a very constant performance," he said.
"Welcoming a Grand Tour winner makes us feel very proud. I believe he will be a good fit for our team."