The actress rested her hand protectively over her blossoming bump as she posed for photographers at the London Film Festival while promoting her latest film Labor Day.
Silver screen star Kate was chic in black skinny jeans, a simple jersey top, a sleek fitted blazer and black heels for the occasion.
The 37-year-old, whose baby is due before the end of the year, wore her blonde hair in loose curls and teamed the sophisticated look with elegant gold jewellery.
She beamed during the Labor Day photocall at the Mayfair Hotel in London alongside co-stars Josh Brolin and Toby Maguire.
Kate recently spoke in a refreshing interview about her body confidence.
"Look. I'm 37 years old," the Revolutionary Road star told Time Out. "We have one life. I don't want to spend my time thinking about the size of my a**e.
"I want to be as healthy as I can be, and I want to have as much fun as I can have. I want to be around for my children. That's it. Those are the priorities. Not getting a flat stomach.
"Don't get me wrong. I like staying fit and healthy. It's all part of a healthy attitude to life."
The Hollywood star, who said she has been "lucky" and not had any major problems in her pregnancy, revealed that she wasn't going to rush into shedding her post-baby weight.
"How does anyone have the time?" said Kate. "Also, let's be real here. Everyone is different. Springing back into shape after a baby — that's not really something that's ever happened particularly swiftly for me. That's just me."
The expectant mum is due to give birth to her first child with husband Ned Rocknroll before the end of the year. The happy parents-to-be were married in December 2012 after a whirlwind romance.
The baby will be a little brother or sister to her 12-year-old daughter Mia from her marriage to Jim Threapleton and her nine-year-old son Joe from her ex-husband Sam Mendes.
Titanic star Kate met Ned — who was born Ned Abel Smith before legally changing his name — while on holiday on Richard Branson's Necker Island.
Ned is the nephew of the Virgin mogul and works on the space travel branch of the Virgin empire, Virgin Galactic, with Princess Beatrice's boyfriend Dave Clark.