The 38-year-old will join the Reds this summer after 14 years of service with the Bundesliga outfit.
Rohrbeck is being brought in to work with the club’s existing medical and sports science team.
Mainz sporting director Rouven Schroder said: “Christopher Rohrbeck has worked for us in a reliable fashion on a high level for many years and was now presented with a chance to switch jobs.
“Even though for us this means losing one of our long-time employees, we wanted to grant Christopher and his family their wish to take on a fresh challenge in Liverpool.