The pair have long been linked to a move to Jumbo-Visma and the moves come as no surprise.
Paris-Roubaix champion Van Baarle comes on board from Ineos Grenadiers to strengthen a Classics line-up that already boasts Wout van Aert, Christophe Laporte, and Tiesj Benoot.
Meanwhile, Kelderman, who started his career at the team when it was known as Rabobank, joins from Bora-Hansgrohe to boost what is already the strongest Grand Tour squad in the peloton.
"It gives us a special feeling Wilco is returning to the team where it all began for him," team directeur sportif Merijn Zeeman said. "The fact that Dylan has also chosen us makes us proud and happy. He has a great palmarès and is a highly appreciated rider in the peloton. We aim for big prizes and with Dylan in our team, we increase the chances of success."
Van Baarle joins having spent the past five seasons at Ineos Grenadiers after turning pro with Garmin in 2014. He had spent three seasons in the Rabobank Continental set-up before that, making the move something of a homecoming.
The 30-year-old has recently enjoyed the best two-year spell of his career, winning Paris-Roubaix this spring to follow up a win at Dwars door Vlaanderen a year ago. He also added runner-up spots at the Tour of Flanders and the World Championships to his palmarès.
"I'm really looking forward to next year. As a Dutch rider in a Dutch team, it feels like coming home. I have closely watched the team's development over the past few years," Van Baarle said in a team press release.
"It was on an upward trend, so I chose Team Jumbo-Visma. With Wout and riders like Tiesj and Nathan [Van Hooydonck], we have a really powerful team, particularly in the Classics. I hope we can perform well in the spring, and I want to contribute to the stage races too. The team deservedly won the Tour with Jonas [Vingegaard] this year and I would like to be part of that next year."
Kelderman, meanwhile, has spent the past six seasons at Sunweb and Bora-Hansgrohe having turned pro with Rabobank back in 2012.
He left the squad back in 2016 and has since gone on to contend for Grand Tour podiums, finishing fourth at the 2017 Vuelta a España, fifth at the 2021 Tour de France, and third at the 2020 Giro d'Italia. The 31-year-old has one victory on his palmarès: the overall at the 2013 Tour of Denmark.
"I'm delighted to start working together again. Even though I had been away for a while, Team Jumbo-Visma felt like my home team," Kelderman said. "I know the people there very well and I've always kept in touch. I think this is the right development in my career. The team has made progress and I'm curious to see where it will lead.
"Team Jumbo-Visma is an ambitious team and I hope to contribute to their goals. I think I still have room for growth and show great things. It goes without saying that the squad has recently enjoyed great success and I hope to support the guys who made it happen in the big races. I also hope to pass on my experience to the young riders. I'm really looking forward to it."
The signings are the first confirmed incoming moves for Jumbo-Visma this off-season, though they have been linked to moves for several other riders already, including Jan Tratnik and Attila Valter.
Among the confirmed outgoing are Tom Dumoulin, who retired last week, Mike Teunissen, who moves to Intermarché-Wanty-Gobert, and Chris Harper, who heads to BikeExchange-Jayco. Elsewhere, Nathan Van Hooydonck and Tiesj Benoot have both signed two-year deals to stay on board at the Dutch squad.
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Daniel Ostanek is Senior News Writer at Cyclingnews, having joined in 2017 as a freelance contributor and later being hired full-time. Prior to joining the team, he had written for numerous major publications in the cycling world, including CyclingWeekly, Rouleur, and CyclingTips.
Daniel has reported from the world's top races, including the Tour de France and the spring Classics, and has interviewed many of the sport's biggest stars, including Wout van Aert, Remco Evenepoel, Demi Vollering, and Anna van der Breggen.
As well as original reporting, news and feature writing, and production work, Daniel also oversees The Leadout newsletter and How to Watch guides throughout the season. His favourite races are Strade Bianche and the Volta a Portugal.