Her performance in Whistle Down the Wind (a 1961 adaptation of the novel written by her mother) saw Mills nominated for the BAFTA Award for Best British Actress and she was voted the biggest star in Britain for 1961.

In the late 1960s, Mills began performing in theatrical plays, making her stage debut in a 1969 West End revival of Peter Pan.

Although she has not maintained the box office success or the Hollywood A-list she experienced as a child actress, she has continued to make films and TV appearances, including a starring role in the UK television mini-series The Flame Trees of Thika in 1981, the title role in Disney's television series Good Morning, Miss Bliss in 1988, and as Caroline, a main character in Wild at Heart (2007–2012) on ITV in the UK.

[1] Mills was 12 when she was cast by J. Lee Thompson, who was initially looking for a boy to play the lead role, in Tiger Bay (1959) which co-starred her father.

[3][4] Bill Anderson, one of Walt Disney's producers, saw Tiger Bay and suggested that Mills be given the lead role in Pollyanna (1960).

[5] The role of the orphaned "glad girl" who moves in with her aunt catapulted her to stardom in the United States and earned her a special Academy Award of Juvenile Oscar, the last person to win the accolade.

[7] Mills received an offer to make a film in Britain for Bryan Forbes, Whistle Down the Wind (1961), based on a novel by her mother Mary Hayley Bell, about some children who believe an escaped convict is Jesus.

[10] In 1963, Disney announced plans to film an adaptation of Dodie Smith's novel I Capture the Castle, with Mills in the role of Cassandra.

Ross Hunter hired her for a British-American production The Chalk Garden (1964), playing a girl who torments governess Deborah Kerr.

[13][14] Mills had a change of pace with Sky West and Crooked (1965), set in the world of gypsies, written by her mother and directed by her father,[15] but it was not commercially successful.

1 in Mexico,) also led to the release of a record album on Disney's Buena Vista label, Let's Get Together with Hayley Mills, which also included her only other hit song, "Johnny Jingo" (Billboard No.

[17] In Forever Young: A Memoir,[18] among other topics, she reveals high points from her early career, as well as struggles with self-esteem[19] and an eating disorder.

Her appeal to regain her funds was eventually shot down, with Mills admitting that at that time, she was worried about going the path of Judy Garland and becoming a "studio asset".

[20] For Universal, Mills made another film with her father, The Truth About Spring (1965), co-starring Disney regular James MacArthur as her love interest.

[citation needed] Shortly after The Truth About Spring, Mills appeared alongside her father and Hywel Bennett in director Roy Boulting's critically acclaimed film The Family Way (1966), a drama about a couple having difficulty consummating their marriage, featuring a score by Paul McCartney and arrangements by Beatles producer George Martin.

[citation needed] Mills made another movie for Boulting, the controversial horror thriller Twisted Nerve in 1968, along with her Family Way co-star Hywel Bennett.

[23] In 1972 Mills again acted opposite Hywel Bennett in Endless Night along with Britt Ekland, Per Oscarsson and George Sanders.

"[25] In 1981, Mills returned to acting with a starring role in the UK television mini-series The Flame Trees of Thika, based on Elspeth Huxley's memoir of her childhood in East Africa.

The show was cancelled after 13 episodes and the rights were acquired by NBC, which reformatted Good Morning, Miss Bliss into Saved by the Bell without any further involvement from Mills.

In 2021, Mills played Michael Sheen's mother in the film Last Train to Christmas, and in 2022 she had a recurring role in the television thriller series Compulsion.

[32] In 2000 she made her Off-Broadway debut in Sir Noël Coward's Suite in Two Keys, opposite American actress Judith Ivey, for which she won a Theatre World Award.

[citation needed] In 2012 she starred as Ursula Widdington in the stage production of Ladies in Lavender at the Royal & Derngate Theatre, before embarking on a national UK tour.