When Han Kang’s surreal, violent novel “The Vegetarian” was published in South Korea nearly a decade ago, literary critics found it baffling. The story stars an unhinged heroine who believes she’s turning into a tree, and features some of the strangest erotic passages in literature. (In one unforgettable scene, Ms. Han renders clichéd sexual metaphors about flowering plants and protruding pistils quite literally.)

The mesmerizing mix of sex and violence was not what fans and reviewers expected from Ms. Han, a celebrated and award-winning poet and novelist.

“It was received as very extreme and bizarre,” Ms. Han said in English during a recent telephone interview from her home in Seoul. “Definitely, readers were surprised.”

Even more surprising was the rapturous reception that followed. “The Vegetarian” became a cult international best seller. Publication rights have sold in nearly 20 countries. It was adapted into a Korean film that played at Sundance in 2010.

Still, Ms. Han, who has been publishing fiction and poetry for more than two decades, remained almost entirely unknown to English-speakers.

That is starting to change, thanks largely to Deborah Smith, a 28-year-old British translator who read a Korean edition of “The Vegetarian” four years ago, when she was studying for her Ph.D. at the University of London’s School of Oriental and African Studies. She was transfixed by the unusual story and vivid, chiseled prose, and attempted to translate it herself, but wasn’t fluent enough yet to capture Ms. Han’s style. A year later, she tried again, and sent a short sample translation to a British publisher, who decided to publish the novel based on the first 10 pages.