The series was developed at Warner Bros. with Riverdale creator Roberto Aguirre-Sacasa taking over as showrunner from I. Marlene King, who had led the original Pretty Little Liars series.

HBO Max gave the show a direct-to-series order of 10 episodes in September 2020, and it is the first entry in the franchise not broadcast on ABC Family/Freeform but instead released on a streaming service.

Charles Gray played former Radley Sanitarium nurse Eddie Lamb in season one, replacing Reggie Austin who originated the character in the 2010 series.

Annabeth Gish reprised her role as therapist Dr. Anne Sullivan, a character first introduced in the original Pretty Little Liars series, for the second season.

Filming took place in Hudson, New York, and at Upriver Studios in Saugerties, New York, during the COVID-19 pandemic, with production running from August 2021 to May 2022.

Filming for the second season was delayed by the 2023 Writers Guild of America strike and then further affected by the actors' strike, before resuming in November 2023 and wrapping in December 2023.

Horror composer Joseph Bishara, known for scoring the Insidious and The Conjuring franchises, wrote the music for the first season, Original Sin.

The opening theme is a remix of "Secret" by the Pierces, the same song used in the original Pretty Little Liars series; it was covered by Transviolet for the second season after a Denmark + Winter cover was used in The Perfectionists.