The 90-minute episode debuted Sunday night on ITV1.
Last year's Season 3 premiere was seen by 8.6 million viewers.
Fresh installments of the early 20th century-set series about a wealthy family and the people who work for them at their country estate will continue to air on ITV1 for seven more weeks. The program will then return in December for an extended Christmas episode, Deadline.com said.
The Season 4 premiere of "Downton Abbey" will air in the United States Jan. 5 on PBS.