Cain, who recently joined Newsmax TV and was set to launch a weekly show, died in an Atlanta-area hospital where he had been critically ill for several weeks.
He was admitted on July 1, two days after being diagnosed with COVID-19.
Ten days before, Cain had attended a rally for President Donald Trump in Tulsa, Oklahoma.
But it is not known for sure where Cain, co-chairman of Black Voices for Trump, was infected. He had been on a whirlwind travel schedule in June, stopping in multiple cities.
"He was one of the most original thinkers in American politics," veteran political consultant Dick Morris told Newsmax, noting "he was creative, had strong convictions, an open mind, and a deep sense of patriotism."