The Silkworm sees the return of war veteran-turned-detective Cormoran Strike as he investigates the mysterious murder of a novelist who wrote disparaging portraits of many of his acquaintances.
Rowling published her first detective novel, The Cuckoo's Calling, under the pseudonym in April last year.
It received good reviews but managed only minimal sales until the lawyer, who has represented Rowling, spilled the beans and his wife's best friend tweeted the news to a journalist. Sales promptly rocketed and the novel shot up to the top of the best-seller lists.
The Silkworm will be published by Little, Brown on June 19. The company also published Rowling's first adult novel, The Casual Vacancy, in 2012.