The 28-year-old German centre-back was a regular for the Dutch side, missing just one match before the season was abandoned in March.
Although he has spent the majority of his career in the Netherlands, he also had a spell with Chemnitzer FC in the 3. Liga between 2014 and 2016, where he had caught the eye of now-Sandhausen coach Uwe Koschinat.
“Even as a young central defender, his presence, due to his height alone, and his very good game structure were unmistakable,” explained the Sandhausen boss in a club statement.
Director of football Mikayil Kabaca meanwhile believes Röseler has “developed into a defensive stabiliser” in recent seasons, pointing out he has helped keep Venlo in the Dutch top tier for three years following their promotion in his first season.
He will likely replace Jesper Verlaat, who is expected to leave at the end of the contract, and Roman Hauk, who will be joining FC-Astoria Walldorf in the summer.