The number was up by 800,000 on the first episode of series one and by 500,000 on the series one average.
Broadchurch series two again features David Tennant and Oliver Coleman as detectives and picks up where the first series, which led to the identification of a murderer in a fictional town in Dorset, left off.
The closest competition for ITV's 30 per cent share of viewing in the slot came from BBC One, which screened FA Cup football between 7.30pm and 10pm.
AFC Wimbledon's unsuccessful attempt at again giant-killing Liverpool attracted an average of 5.6 million viewers, peaking at 6.3 million at 8pm.
Channel 4 was best of the rest at 9pm-10pm with 2.4 million viewers for The Undateables, ahead of Channel 5 with 1.7 million for Benefits: Too Fat To Work.
BBC Two's Rich, Russian and Living in London scored 1.3 million.