According to the BBC, last night's eagerly awaited first episode of the show's fifth series was watched by an average of 3.7 million people, peaking at four million.
The figures mean the drama pulled in its highest overnight ratings for a series opener since the show began in 2013.
The achievement is all the more impressive as it went head to head in the same Sunday night slot as ITV's adaptation of Jane Austen's Sanditon, which was making its debut.
The gangster family epic, set in 1919 Birmingham and starring Irish actor Cillian Murphy as chief protagonist Tommy Shelby, is being shown on BBC One after series four was aired on BBC Two.
Its switch followed the show's win for best drama at last year's TV Baftas.
Penned by Steven Knight, Peaky Blinders focuses on the Shelby family's criminal organisation in the aftermath of the First World War.
A hit across the world, the show includes scenes shot in Yorkshire including in Grade I-listed Bradford City Hall's council chambers.
The new series plunges the main characters into the world of politics, with Tommy Shelby in place as an MP.
It also stars Paul Anderson, Sophie Rundle, Finn Cole, and Helen McCrory, who recently said she was unable to watch the "disgustingly violent" opening episode of the new series.