The 20-year-old actress has enjoyed huge success with the streaming platform, starring in 'Stranger Things' and the 'Enola Holmes' franchise, and Millie has now joked about her relationship with Netflix.
Speaking to Collider, Millie quipped: "You know what, I think I'll forever be in debt to Netflix, because they're my boss. So, I'm going to pay for my subscription ... because I'm going to forever be saying thank you to them for the opportunities they've given me."
Millie has already made two 'Enola Holmes' movies and the actress hinted that she could reprise the character in the future.
Asked about the possibility of making a third movie, Millie simply replied: "Maybe."
The Hollywood star serves as a producer on the franchise and she suggested that she'd love to make another film with Netflix.
Asked if another 'Enola Holmes' movie is in the works, Millie said: "I pay a subscription to Netflix every month ... and that's the tea."
Millie plays the titular character - who is the teenage sister of detective Sherlock Holmes - in the hit film franchise, and she previously admitted that she'd love to return to the role one day.
The actress has become fond of the character over recent years, and she hopes that Netflix will throw its support behind another 'Enola Holmes' movie.
Speaking to Collider in 2022, Millie said: "I mean, obviously I really hope so.
"I love Enola, and I know that, now, people are very much invested in the character and the plot, and I can only hope that Netflix provides that trust and opportunity once more."