The movie The Road to Guantanamo was watched by 1.6m TV viewers when as part of a simultaneous international cinema, DVD and download release.
The film was shot in Afghanistan, Pakistan and Iran
The film about three British Muslims held at Guantanamo Bay camp as terror suspects was shown on Channel 4 prior to release on the other platforms.
The British film is the first international simultaneous release.
In the same Thursday time slot, BBC One's Hotel Babylon was seen by 5.4m while ITV1's Footballers' Wives got 4m.
The movie, which is now on general release in the UK, won a Silver Bear award at the Berlin Film Festival last month.
As well as being on sale as a DVD, the film has been made available to buy or rent as a download over the internet.
Directed by British film-maker Michael Winterbottom, The Road to Guantanamo tells the story of the Tipton Three from the West Midlands, who went to Pakistan to arrange a wedding.
They were picked up in Afghanistan and believed to be terrorist suspects and were eventually released from Guantanamo Bay in 2004 without charge.
The film depicts treatment meted out at the camp
The film, shot in Afghanistan, Pakistan and Iran, was made at a cost of £1.5m.
Winterbottom's other film credits include 24 Hour Party People, Welcome To Sarajevo and A Cock And Bull Story.
On returning from the Berlin Film Festival last month, the actors who play the British inmates were questioned by police at Luton airport under anti-terrorism legislation.
All six people from the film's party were released quickly and not arrested, said Bedfordshire police.