The 23-year-old former Germany youth international made a total of 110 appearances in Bundesliga 3 for Burghausen and is now set to take his bow at a higher level with Karslruhe.
"Rene's a very ambitious player who we've been following for several years," said KSC coach Markus Kauczinski. "He's been playing in this region for a long time and has a lot of talent."
Vollath has already joined his new team mates in their pre-season training camp, and he cannot wait to get into action. "I want to contribute to this team's success," he said. "I feel really happy in this region and that's why I'm all the more delighted that it's worked out."