How Old is Sienna Miller? Age, Partner, and 2025 Baby News
Sienna Miller is 43 years old. Born on December 28, 1981, the British-American actress will celebrate her 44th birthday later this month.
While the number “43” might be the quick answer you were looking for, it barely scratches the surface of why Miller is currently dominating search trends. As of early December 2025, her age has become a central part of a much larger conversation about motherhood, career longevity, and defying Hollywood expectations.
Fresh off the red carpet at the Fashion Awards 2025, Miller has confirmed she is expecting her third child—proving that for her, the forties are not a time for slowing down, but for a “second act” renaissance.
Sienna Miller’s Profile at a Glance
Before we dive into the breaking news and her career timeline, here are the vital statistics you need to know.
| Fact | Details |
| Current Age | 43 Years Old |
| Date of Birth | December 28, 1981 |
| Zodiac Sign | Capricorn |
| Birthplace | New York City (Raised in London) |
| Partner | Oli Green (Age 28) |
| Children | Marlowe (13), Daughter (Born 2024), Baby #3 (Due 2026) |
| Height | 5ft 5in (1.65m) |
| Current Projects | Horizon: An American Saga, Jack Ryan (2025 film) |
The Breaking News: Pregnant with Third Child (2025)
If you have been following British entertainment news this week, you know that Miller didn’t just attend the Fashion Awards 2025 at the Royal Albert Hall on December 1; she made a statement.
Dressed in a custom Givenchy gown, Miller explicitly cradled a visible baby bump, confirming she is pregnant with her third child. This will be her second child with partner Oli Green.
[Editor’s Note on Credibility]
According to official coverage from the British Fashion Council, Miller’s appearance stole the show, marking one of the most high-profile pregnancy reveals of the year. This follows a pattern Miller established with her previous pregnancy, where she famously bared her bump on the red carpet, challenging the old industry norm of hiding pregnancy after 40.
This news is significant because it directly combats the “biological clock” narrative often forced upon actresses. Miller has spoken candidly in Vogue UK about the pressure she felt in her 30s to have more children, revealing that she froze her eggs to alleviate that anxiety. Now, at 43, she is expanding her family on her own terms.
The “Age Gap” & Personal Life: Sienna Miller and Oli Green
A top question associated with “how old is Sienna Miller” often involves her partner, Oli Green.
Oli Green is 28 years old, creating a 15-year age gap between the couple. They confirmed their relationship in 2022 and have since become a fixture on the London fashion scene.
Critics and tabloids initially fixated on the age difference, but Miller has addressed this head-on. In interviews with Elle UK, she described the younger generation (Green’s generation) as having a different, more egalitarian approach to relationships compared to the men she dated in her 20s.
Why This Relationship Works
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Shared Industry: Green is also an actor and model, understanding the demands of her schedule.
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Modern Family Dynamic: The couple co-parents smoothly with Tom Sturridge, Miller’s ex-fiancé and the father of her eldest daughter, Marlowe (13).
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Confidence: Miller has stated that love in her 40s feels less frantic and more grounded than the highly publicized relationships of her youth.
Career Timeline: From Alfie to Horizon
Sienna Miller’s age also serves as a marker for her evolution as an actress. If you remember her primarily from the mid-2000s tabloids, you have missed her transition into a serious character actor.
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The “It Girl” Era (Age 20-25): Miller exploded onto the scene with Alfie (2004) and Factory Girl (2006). This era was defined by her relationship with Jude Law and her “boho-chic” style, often overshadowing her performances.
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The Critical Pivot (Age 30-35): Entering her 30s, Miller sought grittier roles. She earned acclaim for The Girl (playing Tippi Hedren) and her role as Taya Kyle in Clint Eastwood’s American Sniper.
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The Renaissance (Age 43): Today, Miller is at a career peak. She plays a pivotal role in Kevin Costner’s massive western epic, Horizon: An American Saga. Furthermore, [Screen Daily] recently confirmed her casting in the upcoming Jack Ryan feature film, solidifying her status as a bankable action-drama star.
Sienna Miller’s Style Evolution
You cannot discuss Miller without touching on fashion. Her age has not diminished her influence; it has refined it.
[Style File: Then vs. Now]
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2004 (The Glastonbury Era): Miller single-handedly popularized the “boho” look—coin belts, Ugg boots, and floppy hats. She was the face of carefree 20s rebellion.
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2025 (The Modern Matriarch): At the 2025 Fashion Awards, her look was structured, elegant, and maternal. She has traded the coin belts for Schiaparelli and Givenchy couture. She remains a muse for designers not because she chases trends, but because she sets them.
FAQs
When is Sienna Miller’s birthday?
Sienna Miller was born on December 28, 1981. She will turn 44 in late 2025.
What is the age difference between Sienna Miller and Oli Green?
There is a 15-year age gap. Sienna is 43, and Oli Green is 28.
How many children does Sienna Miller have?
Currently, she has two children: her eldest daughter Marlowe (born 2012) and a second daughter (born early 2024). She is currently pregnant with her third child, due in 2026.
Is Sienna Miller pregnant in 2025?
Yes. She confirmed her pregnancy by debuting her baby bump at the Fashion Awards on December 1, 2025.
Who is the father of Sienna Miller’s baby?
Her partner, Oli Green, is the father of her second child (born 2024) and the baby she is currently carrying.
How tall is Sienna Miller?
She stands approximately 5ft 5in (1.65m) tall.
What are Sienna Miller’s latest movies?
She stars in Horizon: An American Saga (Chapters 1 & 2) and is currently in production for the new Jack Ryan film.
Summary
At 43 years old, Sienna Miller is rewriting the script on what it means to be a woman in Hollywood. She is not just an actress or a style icon; she is a mother of three (soon-to-be) who has successfully navigated the transition from tabloid fixture to respected artist.
Whether you are searching “how old is Sienna Miller” because of her recent pregnancy announcement or her role in Horizon, the answer reveals a woman in her prime.
Interested in more UK entertainment news? [Read latest coverage on the 2025 Fashion Awards winners here].
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