Soros, who was born in Hungary in 1930 and later survived the Nazi Holocaust before emigrating to the United States, and his foundation have been the target of harsh criticism from Hungary's strongman Orban and his right-wing nationalist government.
"The government of Hungary has denigrated and misrepresented our work and repressed civil society for the sake of political gain, using tactics unprecedented in the history of the European Union", OSF president Patrick Gaspard said in a statement.
The decision to close the groups' offices in the country of Soros's birth is the grim culmination of years of struggle to work in an increasingly hostile environment. The group now has annual expenditures of over $940 million, operates in over 100 countries across the globe, with 26 national and regional foundations and offices.
The legislation, as it was written before the election, would force aid agencies working with migrants to apply for and receive national security clearance from the Interior Ministry. In June, the parliament in Budapest is expected to pass a law criminalizing the work of foreign organizations, especially those that help refugees, and many of these are supported by the OSF.
OSF said the move follows steps by Orban to "impose further restrictions" on non-governmental organizations. The legislation is likely to come up for a vote within the next month.
With Open Society deciding to leave, Jarabik said Orban has now achieved one of his primary goals of forcing out political foes. "It has become impossible to protect the security of our operations and our staff in Hungary from arbitrary government interference", CNBC added.
Another Soros institution funded by Soros, Budapest's Central European University, may also be forced to shutter operations in Hungary. The law also barred the school from admitting new students after January 2019 if it does not reach a compromise with the government.
As hundreds of thousands of people streamed through Hungary bound for Western Europe and with Budapest train stations resembling squalid refugee camps, Orban erected a fence on Hungary's border with Serbia. This has caused Brussels to issue threats to the region to cut off funding and other sanctions.
No figure featured more prominently in the campaign than Soros.
Viktor Orban, the Hungarian leader, has spent more than €100 million in state funds on propaganda to demonise George Soros, the financier's charity claimed as it announced it was pulling out of Budapest.