Liar was announced on 15 April 2016 as the very first full production from the newly formed company Two Brothers Pictures, created by Harry and Jack Williams.

The miniseries was jointly commissioned by American cable network SundanceTV and British broadcaster ITV on 30 September 2016, with French network TF1 and Australian network Seven also ordering the series.

Filming took place in London and Kent starting in November 2016, with the marsh scenes shot in Tollesbury, Essex, and Laura's seaside hometown filmed in Deal and Kingsdown, Kent.

Additional inner-town sequences were shot in Brockley, Nunhead, Shortlands (for Episode 3), South Ealing, and Edinburgh (for Episode 4).

The series premiered on ITV on 11 September 2017 at 9pm, in the exact same broadcast slot as another Two Brothers Pictures series, Rellik, which premiered on BBC One.

As of 2015, nine international remakes of Liar had been produced in countries including Italy, Spain, Germany, France, Turkey, Greece, Slovakia, Malaysia, and India (as Marzi), with a Korean remake planned for 2026.

The Philippine broadcaster ABS-CBN acquired the series and aired a Tagalog-dubbed version on its Kapamilya Channel starting 10 March 2025, years after the original UK broadcast.