Bevin, the New Zealand time trial specialist, joins from Israel-Premier Tech, while Vanhoucke, the Belgian climber, joins from Lotto Soudal.
With Thymen Arensman and Søren Kragh Andersen among five riders confirmed as leaving DSM, the pair are the second and third new faces for the Dutch team.
19-year-old British rider Max Poole will also join the WorldTour team, stepping up from the Team DSM Development squad after a string of good results in 2022.
"I am looking forward to joining an organisation with a strong ethos and professional environment at Team DSM," said Bevin, who joins on a three-year contract.
"I believe that I can bring a lot to the team with my experience as a rider, but also in turn get more out of myself as an athlete with them too."
Bevin cut his teeth in New Zealand before turning fully professional in Europe with the team now known as EF Education-EasyPost. He spent three years at BMC Racing/CCC Team before joining Israel-Premier Tech in 2021.
The 31-year-old has put most of his energy into time trialling, twice winning his national title and placing fourth at the World Championships in 2019, but has also become an increasing threat in uphill or reduced bunch sprints.
In 2019 he won a stage of the Tour Down Under on a drag finish, while this year he has enjoyed his best season, with a stage win and overall title at the Tour of Turkey as well as a stage of the Tour de Romandie.
"Patrick is an experienced professional having spent several years in the bunch, showing off his all-round abilities. He’s taken time trial wins, reduced or uphill sprint wins combined with some strong climbing performances," said Team DSM head coach Rudi Kemna.
"We’re looking forward to working with him and we think that there is still more to get out of his talent. Especially when we look to the sprints after hard days, but also over the hills in general – he has a rider profile that we think suits the hilly classics."
Vanhoucke, 25, joins to strengthen the team's climbing department and their general classification ambitions.
The Belgian won the Piccolo Giro di Lombardia as an U23 and is now in his fourth season as a professional with Lotto Soudal.
He caught the eye with a strong first week at the 2020 Giro d'Italia, while other notable results include runner-up finishes at the 2021 Tour de l'Ain and 2022 Sibiu Tour. He joins on a two-year contract.
"I was attracted to the guidance in the team and how in general riders improve with them. They are also a team that has already had a lot of GC successes in Grand Tours in the past and have a lot of knowledge," said Vanhoucke.
"It will be a new step in my career, and I am curious to see how I will improve as rider with them and what I can learn from the team as well as the more experienced riders."
Kemna added: “Harm had a really good U23 career and has taken steps in his development each season as a pro. He’s more of a traditional pure climber but someone that has also taken good GC results because of that.
"We want to give him the opportunity to further improve and step-up his climbing abilities even more with the team. Still only 25 years old, he has the room to improve, and we think he can make that progression with a specific and well-designed training and race program for the right races."