Doctor Who: The Woman Who Fell to Earth was watched by 8.2 million viewers, a share of 40.1% of the total TV audience, according to unofficial overnight figures.
The audience grew throughout the episode, peaking at 8.52 million for the final fifteen minutes.
The rating makes Doctor Who the third highest rating of the week, just behind two editions of Strictly Come Dancing.
It is the highest overnight rating for the series for a regular episode for over ten years. The debut episode of the Twelfth Doctor, Deep Breath, had an overnight rating of 6.8 million viewers, while the debut episode of The Eleventh Doctor, The Eleventh Hour, had 7.7 million, with 0.3 million also watching on BBC HD, making a total of 8.0 million. The last regular episode to top this figure was Journey's End in 2008, with an overnight figure of 9.4 million.
The highest rating for Sunday was for the results show of Strictly Come Dancing with an average of 9.04 million watching.
ITV's highest-rated programme was The X Factor, with 4.69 million watching. Against Doctor Who, 5 Gold Rings had 2.71 million watching.
Official figures, which will be released next Monday, will include those to recorded the episode and watched it later. They are expected to be considerably higher than the initial figures.