HBO initially denied reports from January 2021 that a Harry Potter television series was in early development, though talks between Warner Bros. Discovery CEO David Zaslav and J.K. Rowling later confirmed the project was moving forward.

The series is planned to span a decade, with each season faithfully adapting one of the seven Harry Potter novels; production on the first two seasons was set to be filmed back-to-back.

Casting directors auditioned roughly 40,000 children for the roles of Harry, Ron, and Hermione, holding in-person auditions in Manchester, Scotland, Ireland, and Cardiff.

Dominic McLaughlin won the role of Harry Potter by performing a poem he had written himself about a weekend in his life, while Arabella Stanton auditioned with William Ernest Henley's poem 'Invictus'.

Actors considered for adult roles before final casting included Mark Rylance and Mark Strong for Dumbledore, Sharon Horgan and Rachel Weisz for McGonagall, and Brett Goldstein for Hagrid.

Paapa Essiedu's casting as Severus Snape drew backlash from some fans because the character is described as white in the books, and Essiedu revealed in March 2026 that he received death threats and racist abuse over the role.

Warwick Davis reprises his role as Filius Flitwick from the original film series, while Paul Whitehouse, cast as Argus Filch, had previously played Sir Cadogan in Harry Potter and the Prisoner of Azkaban though his scenes were largely cut.

Principal photography began in July 2025 under the working title 'Dark Train' at Warner Bros. Studios Leavesden, the same location where the original eight Harry Potter films were shot, and a temporary school for up to 600 child pupils was built on site.

The production crew spent over a week filming on the Île de Sein in Brittany around the Tévennec Lighthouse, and later shot scenes in Cornwall locations including Cadgwith, Carnglaze Caverns, and Kynance Cove.

Prince William and Princess Catherine visited the Hogsmeade Station set built at Windsor Great Park with their children George, Charlotte, and Louis during filming.

The production used animatronics to create animal prototypes, including 10 owls each fitted with 36,000 feathers and two rats designed to play Scabbers.

Hans Zimmer and his company Bleeding Fingers Music were announced to compose the score for the series.

The teaser trailer released on 25 March 2026 became the most-viewed trailer in HBO and HBO Max history, amassing 277 million views within its first 48 hours.