Soros's Open Society Foundations (OSF) organization said it would continue to support human rights work in Hungary as well as projects linked to the arts, media freedom, transparency, education and healthcare, but that it would move its Budapest-based global operations and staff to Germany.
Orban and Soros have clashed over the 2015 European migration crisis. "It has become impossible to protect the security of our operations and our staff in Hungary from arbitrary government interference", CNBC added.
Patrick Gaspard, president of the Open Society Foundations, said on Tuesday that Budapest had "denigrated and misrepresented" the organization's work and repressed civil society "for the sake of political gain".
The 54-year-old premier, reelected for a third consecutive term last month, has long accused Soros of orchestrating immigration into Europe.
"We are going to reaffirm those elements of our sovereignty which are under attack", Orban spokesman Zoltan Kovacs said in a statement.
A Hungarian government billboard featuring George Soros, with the words translated to "Don't let George Soros have the last laugh" is seen at a transit stop in Budapest on July 6, 2017.
The pro-democracy group said it was pulling out a day after the right-wing government of Prime Minister Viktor Orban announced it would tighten restrictions on non-governmental organizations, under a law dubbed the "Stop Soros " bill. Since then he has donated billions of dollars to foundations across the world, with the first in Hungary opening in 1984 to promote freedom of speech during communism. 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.
According to the Open Society Foundations' statement, the closure in Budapest will impact more than 100 staff based there, about 60 percent of whom are Hungarian.
"Orban is now trying to elevate the conservative revolution in Europe. and they believe this is going to strengthen Hungary's position in Europe", said Balazs Jarabik, non-resident scholar at the Carnegie Endowment for International Peace. The Hungarian government opposes the Open Society's open immigration policies. The bill says that all NGOs which "support illegal immigration" need to be registered, while any NGO which gets money from overseas must pay a 25-percent tax.