Stamsnijder has ridden for Sunweb, and the team's previous guises as Giant-Alpecin and Argos-Shimano, for the past seven seasons, having previously ridden for Leopard Trek, Rabobank and Gerolsteiner, and for the Rabobank Continental team as an under-23 rider.
Just 33, the reason for Stamsnijder's retirement is given by the team as "a persistent injury that prevents him from performing at the highest level", and is reported on tubantia.nl as being intestinal problems that began in 2017.
"I look back on a really great career," Stamsnijder said on Team Sunweb's website. "Together with the team, we've reached so many highs, and I'm thankful to have been a part of that."
Stamsnijder rode the Vuelta a España five times and the Giro d'Italia seven times during his career, including in 2017 when he was part of the squad that helped Tom Dumoulin to take the Giro title.
"After 12 years at the highest level, this is my moment to quit," he said. "I've had some problems with an injury over the past year-and-a-half, which hasn't been easy.
"I'm really looking forward to focusing on my career outside of being a professional rider, and I'm happy to have the opportunity to start a new chapter in my career with the team's partner, DSM," said Stamsnijder, who's the son of 1981 cyclo-cross world champion Hennie Stamsnijder.
"During my time on the bike, I realised how important innovation is. My role at DSM will involve analysing their recent innovations in nutritional ingredients, materials and suncare products to see if these can enhance performance within Team Sunweb," he said.
"We're really grateful for the years we've had Tom as a rider in our team," added Sunweb's head coach, Rudi Kemna. "Both on and off the bike, Tom was a valuable team player and had his share in many of the successes that we've had as a team.
"It's great that he'll continue to work closely with the team in his new challenge with our partner DSM; this is a really exciting opportunity for him and we are delighted to benefit from his experience through his new role."