The Harry Potter creator, purporting to be Robert Galbraith, a former military man, won plaudits from top crime writers who read the book without knowing she was behind it.
'The Cuckoo's Calling', which features a war veteran turned private investigator called Cormoran Strike, was published to critical acclaim in April.
One reviewer described it as "a scintillating debut".
Another praised the "male" author's ability to describe women's clothes.
Rowling's authorship was uncovered by 'The Sunday Times' after it investigated how a first-time author "with a background in the army and the civilian security industry" could write such an assured debut novel.
More From This Section
"I had hoped to keep this secret a little longer because being Robert Galbraith has been such a liberating experience. It has been wonderful to publish without hype or expectation, and pure pleasure to get feedback under a different name," Rowling said yesterday.
The clues that pointed to Rowling's authorship include the fact that she and "Galbraith" share an agent and editor.
The book was published by Sphere, part of Little, Brown, which published 'The Casual Vacancy', Rowling's novel for adults, last year.
The book's style and subject matter bore similarities to her other works, the paper said.