Germany had asked for the case to be thrown out on the basis of sovereign immunity, which generally prohibits US courts from hearing claims against foreign governments.
The justices will hear arguments arising from a 2015 lawsuit filed in US federal court in Washington in which heirs of the art dealers said Germany owes them either the return of the artwork or more than $250 million in damages.
The court also agreed to hear Hungary's bid to avoid litigation brought by US citizens who survived that nation's World War Two-era campaign of genocide against its Jewish population.
The plaintiffs in the Germany case have said they are the rightful owners of a 17th century collection of medieval art known as the Welfenschatz that includes gem-studded busts of Christian saints, golden crucifixes and other precious objects.
In 1935, a group of Jewish art dealers in Germany sold the collection to the state of Prussia, then being administered by prominent Nazi official Hermann Goering. The plaintiffs said that the sale was a "sham transaction" made under duress and that their ancestors received just 35 percent of the art's market value.
In the 2015 lawsuit, the plaintiffs sought either money or the return of the Welfenschatz, which is currently in the possession of the Prussian Cultural Heritage Foundation, a German governmental entity.
A federal judge in Washington ruled in 2017 that because the organized plunder of Jewish property by the Nazis was part and parcel of their later genocide of the Jews - a crime under international law - the American court had jurisdiction to hear the case.
The US Court of Appeals for the District of Columbia Circuit narrowed the case in 2018, saying claims could proceed against the Prussian Cultural Heritage Foundation but not against Germany's government itself.
The Hungarian Holocaust survivors, who seek to represent a class of survivors who have been injured in similar ways, are seeking restitution for possessions taken from them and their families when they were forced to board trains destined for concentration camps.Hungary has appealed a decision by the US Court of the Appeals for the District of Columbia Circuit that revived the litigation.