Deep Breath saw the newly regenerated Twelfth Doctor and companion Clara arrive in Victorian London where a dinosaur was on the rampage and people were spontaneously combusting.
At its peak, the episode was seen by 7.3 million viewers.
The show’s average audience equates to a 32.5% audience share and is the highest for any season opener since 2010.
Final figures, including who recorded the show and watched it later, will be calculated by BARB and released next week.