Sienna Miller, 42, hits the red carpet in an extremely plunging black dress that shows off her ample cleavage as her incredible post-baby ‘Siennaissance’ continues

Sienna Miller made sure all eyes were on her when she posed spectacularly at the premiere of Marion in Venice on Friday.

The 42-year-old actress showed off her ample cleavage in a plunging black strappy dress at the glitzy launch of the short film, which she executive produced.

Sienna looked stunning as she teamed the simple black ensemble with stylish sunglasses and a large silver necklace.

The mother of two, who welcomed her second child and first with boyfriend Oli Green in December, appeared to be enjoying a child-free day as she was helped aboard the boat.

The star seems to be well and truly in the ‘Siennaissance’ era now, as less than a year after the birth of her child, she continues to come up with her plethora of fashionable looks.

Sienna Miller, 42, hit the red carpet in a plunging black dress that showed off her ample cleavage as her incredible post-baby ‘Siennaissance’ continued at the Venice Festival on Friday

Sienna showed off a lot of skin in her ensemble and looked amazing as she paired the simple black ensemble with stylish sunglasses and a chunky silver necklace

The actress set pulses racing in the eye-catching velvet dress as she attended the premiere of the film Marion

Marion focuses on the French tradition of bull jumping at La Course Landaise. The synopsis reads: ‘As Marion prepares to be the only woman on the team, the film explores her struggle against misogyny and prejudice.

‘One woman’s journey through an all-male world – juggling motherhood and the aggressive pursuit of her passion. The film blends fiction and reality, creating a gripping thirteen minutes of suspense.’

Sienna was last seen with her boyfriend, 27, last month on a romantic holiday in Saint-Tropez.

The couple’s sunny trip comes after they welcomed their first child, a daughter, in December 2023.

Sienna already has a 12-year-old daughter, Marlowe, from her previous relationship with actor Tom Sturridge, 38.

Her new boyfriend, Oli, an actor 15 years her junior, is just like her — instinctive and a free spirit. In an interview earlier this year, she explained, “I think you either live your life cautiously or you take risks.”

She added that regardless of her choices, she has now finally found peace.

“I’ve felt the need to really prove something for a long time, and I see that in the choices I’ve made. I’ve pursued roles that were really heavy, really dramatic, and emotionally challenging, because I felt like I was probably going to be seen as frivolous. I’m completely over that now.”

The star appears to be well into her ‘Siennaissance’ era as she continues to rock a plethora of fashionable looks less than a year after having her second child.

Sienna, who served as an executive producer on the short film, proudly posed for snaps at the premiere

Two men helped the star keep her balance as she walked onto the boat in her beautiful dress

The mother of two, who welcomed her second child and first with boyfriend Oli Green in December, appeared to be enjoying a child-free day as she was helped aboard the boat

The star seems to be well and truly in her ‘Siennaissance’ era as she continues to show off a plethora of fashionable looks less than a year after the birth of her child.

She completed her look with a pair of simple black heels

Sienna’s pregnancy was revealed during an exotic holiday in August last year, where she spent a day at the beach and showed off her blossoming baby bump

Sienna made heads turn during her debut at this year’s Venice Film Festival

Kevin Costner also arrived in Venice ahead of the premiere of his film Horizon: An American Saga

The actor looked handsome as he took a water taxi to the festival

Sienna’s pregnancy was revealed during an exotic holiday in August last year, when she spent a day at the beach, clearly showing off her growing belly.

She later appeared on the cover of Vogue, where she showed off her bare stomach alongside Marlowe and Oli. She spoke about her pregnancy for the first time, announcing that she was expecting another girl.

During the rare interview, the Horizon: An American Saga star spoke candidly about how “unplanned” her pregnancy was.

She added that Marlowe had wanted a brother or sister for some time and admitted she felt “more psychologically prepared” than she did with her firstborn.

Sienna said: ‘I was very lucky. I wasn’t necessarily trying to get pregnant. This came as a complete surprise and biologically it was something I could do.’

Discussing what’s different this time around, she explained, “I have expectations that I didn’t have before. I feel much more psychologically prepared than I was with Marlowe.

‘It was quite a shock, the reality. I hadn’t thought about it, I don’t think you can prepare for it. In my mind I imagine it will be the most beautiful thing, but I think I forgot.’

Sienna then addressed the stigma surrounding pregnancy as an older woman, admitting that she has struggled with her own prejudices around the topic for some time.

She said: ‘I think people are content with a way of life that has existed for years, but it is very misogynistic and patriarchal.

‘Like if I’m the older woman who’s in a relationship with a younger person, or if I’m pregnant after 40, then that’s irresponsible and sad for the child, it’s all double standards.’

She added: ‘I’d like to get to the point where I no longer feel the need to joke about being a parent and having a child, to show that I get the joke.’