Which Harry Potter book by J.K. Rowling was the first to sell one million copies in the United Kingdom?

Harry Potter and the Goblet of Fire was the first J.K. Rowling book to sell one million copies in the United Kingdom.

Published in 2000, the fourth novel was released amid enormous anticipation. Its first-day sales in Britain were exceptionally high, and it became the first book to sell more than one million copies in the country within a single day. That performance demonstrated how the series had expanded from a successful children’s franchise into a mass-market publishing event.

The novel is also notably longer than the first three books. Its plot introduces the Triwizard Tournament, the arrival of students from Beauxbatons and Durmstrang, and the return of Lord Voldemort to physical form. These larger events helped make the fourth book a major turning point in the series.

The record is sometimes mixed up with the later books’ first-week or global sales figures. Goblet of Fire’s distinction concerns its United Kingdom launch and its million-copy first-day result.