The figure represented a 44 per cent share of the total audience watching television on Sunday lunchtime.
The third day also secured Channel 4 its best share of total television viewing for a Saturday in its 22-year history, with a 15.1 per cent share of the TV audience.
Viewing on Saturday also peaked at 4.1 million at around 6.15pm.
The peak figures were the second highest for cricket on Channel 4, surpassed only by the climax of England's victory at Lord's over the West Indies in 2000, which attracted 5.2 million.
The Edgbaston match attracted peak viewing figures of 2.8 million on the first two days.
The ratings helped Channel 4 to a 12.5 per cent share of all viewing during the week, its best performance for 13 months.
It is the free-to-air broadcaster's last season covering Test cricket before the contract passes to pay-TV channel Sky Sports.
