Powless, 21, rode for the Axeon Hagens Berman development team for the past two seasons, taking fourth in the Tour of Utah this year and ninth in the Tour of California in 2016 as the race's best young rider. Powless, who was third in the Le Triptyque des Monts et Chateaux this year, has also won stages at the Tour de Beauce, Baby Giro and Tour de l'Avenir.
"Powless is considered as one of the most talented riders of his generation," said LottoNL-Jumbo director Merijn Zeeman. "It's great news that he has chosen to join us, since he had several different opportunities.
"He prefers our team because he sees and believes that we develop young riders in a good way and that they improve while being prepared for the next level by us," Zeeman said. "It's a nice confirmation of our policy and a proof for us of being on the right way.”
Powless' fellow American Alexey Vermeulen is currently in the second year of a two-year deal with the Dutch team, but there has been no word if he'll re-sign with the team.
Powless, who was previously linked to Cannondale-Drapac, said he was excited to be joining the Dutch WorldTour program.
"I'm almost at a loss for words at the moment," Powless said. "I've been aiming to race in the WorldTour for a very long time, and now I'll finally get the opportunity to do so with team LottoNL-Jumbo.
"My interactions with the team and staff up to this point have already exceeded my expectations of what I thought a world tour team would be like," Powless said. "I can't wait to see what the future has in store."