A partner in JAB Holding, Peter Harf, said the Reimann family was shocked by links to Nazi abuses, discovered by the Bild am Sonntag newspaper in archives.
"[Albert] Reimann senior and Reimann junior were guilty... they belonged actually in prison," said Mr Harf.
The family will donate €10m (£8.6m) "to a suitable organisation", he said.
Bild am Sonntag reports (in German) that female slaves from Nazi-occupied eastern Europe - treated as racially inferior - were beaten and sexually abused at Reimann premises in Ludwigshafen, in the Rhineland. Among them was a Russian maid.
The Reimann family fortune today is estimated at €33bn, which would make it Germany's second-wealthiest family.
JAB Holding, their investment firm, has major stakes in various consumer brands, including Keurig Dr Pepper beverages, Coty Inc beauty products, Jacobs Douwe Egberts coffee and the Pret A Manger sandwich chain.
Albert Reimann senior died in 1954 and his son in 1984. It has emerged that both were enthusiastic Nazis, whose company used slave labourers.
But it has taken more than 70 years for those dark connections to come out.
Millions of ethnic Slavs were forced to toil under harsh conditions in Nazi factories or on farms, usually for little or no payment. Jews were also used as slave labour, though generally Jews were slaughtered by Hitler's SS.