The announcement came as the United Nations held its first-ever general assembly on refugees and migrants in New York. The Syrian civil war has put a spotlight on these issues, as hundreds of thousands of refugees crossed the Mediterranean last year.
"I have decided to earmark $500m (£383m) for investments that specifically address the needs of migrants, refugees and host communities. I will invest in startups, established companies, social-impact initiatives and businesses founded by migrants and refugees themselves," Soros wrote in the Wall Street Journal.
He continued: "Although my main concern concern is to help migrants and refugees arriving in Europe, I will be looking for good investment ideas that will benefit migrants all over the world."
Emerging digital technology was highlighted as a particularly promising opportunity by Soros, who said that advances in the sector could improve people's access to government, legal, financial and health services.
"Private businesses are already investing billions of dollars to develop such services for non-migrant communities," he added.
The investments will be owned by Soros' non-profit organisations and any profits will go to programmes at the Open Society Foundations which he chairs, including those that benefit migrants and refugees.
At the end of 2015, there were 65.3m forcibly displaced people. They included 21.3m refugees, 40.8m internally displaced and 3.2m asylum seekers.