No, Oscar Micheaux doesn't count in this case, because, again, I'm only considering books that have been optioned and adapted by Hollywood studios.
A headscratcher... so I went through a few books of mine that cover black film history, notably books by Donald Bogle, bell hooks, Manthia Diawara, Ed Guerrero, and others. And I think I found the answer within the pages of Guerrero's Framing Blackness: The African American Image In Film (a recommended read if you haven't read it already).
On page 28, in the chapter titled Hollywood's Inscription Of Slavery, Guerrero mentions a 1946 book by African American author, Frank Yerby, titled, The Foxes of Harrow.
Guerrero doesn't explicitly state that the book is indeed the first by a black author to be adapted by a Hollywood studio (20th Century Fox in this case), so I wasn't immediately certain. Naturally, I looked up Yerby and the book to find mentions on a number of sites (Wikipedia, IMDB, The New Georgian Encyclopedia, and others) that all say Yerby was the first African American author to see his work adapted to film by a Hollywood studio.
So what's this book about?
Well, first, it's worth noting that it was a best-seller; it centered on "an Irish rascal and inveterate gambler who wins a vast estate while gaming in New Orleans."
In 1947 John M. Stahl directed a film based on the book, which starred Rex Harrison and Maureen O'Hara. It was nominated for an Academy Award for Best Art Direction.
The novel the film is based on appears to be out of print, although you can buy early editions from resellers via Amazon.com as I learned.
The film isn't readily available either; the only site I found it on was on Amazon, but it's the Spanish version, in region 2. It's definitely not on Netflix. Maybe try eBay.
Clearly, the book's story isn't centered on black people, which would partly explain studio interest at the time; as for its content... in Ed Guerrero's book, he praises the film (not necessarily Yerby's book), as one of a number of 1940s movies that "increasingly sensitized Hollywood to the African American perspective on slavery..." He highlights 2 scenes from the film as examples of an "undercurrent of... cultural resistance to slavery and Christianity."
In the first, slaves are shown practicing a voodoo ceremony; and in the second, a black mother throws herself and her baby into a river to avoid having to go on living in slavery (almost as if addressing the scene from Birth Of A Nation, when the white woman jumps off a cliff to avoid submitting to a black man).
So, clearly there were subplots involving black people. But, as I said, that was the movie adaptation, not the book.
With regards to the book, I found this piece in the New Georgian Encyclopedia: "Yerby was often criticized by blacks for the lack of focus on or stereotypical treatment of African American characters in his books. Thus, ironically, while Yerby held the distinction of being the first best-selling black novelist, he also became one of the most disparaged for his lack of racial consciousness. In response to this criticism, Yerby argued that "the novelist hasn't any right to inflict on the public his private ideas on politics, race, or religion." He later amended this stance to a degree, and in the late 1950s and 1960s he wrote novels that touched upon issues of race and southern culture..."
Hmm... alright. Noted :)
Yerby died in 1991 by the way. He was 75 years old.
The above photo was taken in 1983.