The pair announced the sad news with a joint statement.
“Over the past few months we’ve come to the conclusion that the best way forward for us as a family is to separate as a couple. It is with great love, respect, and friendship in our hearts that we look forward to raising our children together and exploring this new phase of our relationship."
“While we appreciate your curiosity and support, we ask the press to be mindful of our children and respect their right to privacy," the joint statement read.
The couple, who have never married, share two sons together nine-year-old Alexander "Sasha" Pete and seven-year-old Samuel "Sammy" Kai.
Despite Naomi and Liev parting ways romantically, the pair will always put their two kids first.
Just last week, Liev won hearts when he walked the red carpet with his son Sasha at The Emmys.
The dapper duo worked the red carpet in matching suits however in light of his split with Naomi, it now seems there was more at play in his choice of date.
Despite not being there, the mum-of-two couldn't have been more excited to share a snap of her two boys.
"Dapper duo here... #twinning #crushingit #goodluck #raydonovan @lievschreiber #proudbeyondwords!" The Aussie penned alongside a photo of Liev and Sasha, indicating that their break-up has been amicable.
Watch Liev talk about his wife in the player below!... Article continues after the video...
Just like former lovers and Hollywood heavyweights, Brad Pitt and Angelina Jolie, Naomi and her longtime love have starred in three films together including The Painted Veil and Movie 43.
But it is their most recent project, The Bleeder, that may have been the final straw.
The biographical sports drama film, which Liev stars and produces in, was released earlier this month. In the flick, the pair play former partners.
Chatting to the Huffington Post about working with her partner, Naomi admitted it was challenging.
"It’s definitely different," she mused, before adding, "But I like that challenge!"
"You are a little bit more nervous in a way because that person knows you so well and so it’s hard to hide things."
"You’ve really got to be on your game and in your most truthful place. And I’m working with an accent, a certain way of moving, it was definitely hard and on the first day or two. I wish we’d had more time on the set together because we’d have completely relaxed into it. I think fifty percent of the time, I was quite nervous."
This year, Naomi spoke candidly about their relationship during a March interview with Los Angeles Confidential.
“Relationships are hard whether you're famous or not. I don't know anyone who doesn't have to work on it. Being an actor doesn't change anything,” the 47-year-old actress admitted.
“I’m sure it's the same if you're a doctor or a couple of lawyers. You have high-pressure jobs, lots of hours, stresses that come unexpectedly - and you have to figure out how to be present in the midst of it all.”
While marriage wasn't something that the pair considered, the British-born starlet admitted their relationship transcended conventional traditions.
"We're very much together. We just don't have that certificate, and that's okay with both of us," Naomi told Easy Living back in 2011.
"Maybe one day, we'll just wake up and go, 'Hey, let's do this.' And maybe not."
One thing is certain, Naomi and Liev always had a lot of raw chemistry.
"I had a strong attraction to him," she told Marie Claire magazine.
"He is handsome and very masculine. I love strong men, but he's just got a great look and intense eyes...and that voice," she mused.
It was that attraction that encouraged Naomi to make the first move.
Recalling how things got started, she told Allure that she was introduced to the handsome star at the 2005 Metropolitan Museum of Art's Costume Institute Gala. And keen to get the ball rolling, she took matters into her own hands.
"It was a lot more ballsy than I would ever normally be," the actress explained to Allure in 2013.
"Normally I want a guy to make the first move, and he wasn't."
"Then he got up to say he was leaving and I was like, 'Oh s*. Probably another couple years are going to pass by.' I was wildly attracted to him and his work, so I said something cheeky as he was about to walk out."
"I said, 'Don’t you want my digits?' Because I couldn't possibly say, 'Would you like my phone number?'"
Clearly it worked out!
"It made him laugh," she explained, adding, "He texted me five minutes later saying, 'Would you like to go for a drink now?' And I said, 'No, I'll meet you for breakfast tomorrow.""