Doctor Who: The Star Beast had an overnight audience figure of 5.08 million viewers in the UK.
Doctor Who was the second most-watched television programme on Saturday night behind Strictly Come Dancing which had 7.67 million watching. ITV had 4.83 million watching the reality programme I'm a Celebrity Get Me out of Here.
The figure shows a large increase over the previous season of Doctor Who with The Power of the Doctor having an overnight figure of 3.710 million.
The figure is an estimate of the number of people who watched the programme on the day of transmission. It will be updated next week to include those who watch the programme on catch-up services.
The Appreciation Index for the episode, a measure of how much the audience enjoyed the programme, was 84, the highest score since World Enough And Time in 2017.
The new episode was available globally on Disney+ where it is currently classed as the 3rd most-watched film worldwide. It is currently in first position in Australia, New Zealand, Singapore and Turkey.