Cameron Diaz and Benji Madden just marked their 10th anniversary with a rare glimpse into their marriage.

Cameron Diaz and Benji Madden have kept their relationship pretty private over the years. But to mark their 10th anniversary, the musician shared a rare glimpse into their marriage.

Sharing a solo photo of Diaz in glam, as well as a couple selfie on Instagram, Madden, 45, wrote: "This is my QUEEN ❤️ I celebrate this BAD ASS WOMAN.

"Wife, Mommy, friend, partner, Boss, and lover. We just hit 10 YEARS married on January 5th and every year only gets more fulfilling."

He went on to call their relationship "special", "never perfect", but "always real — always reliable".

"Every day getting to have my best friend with me ride or die… what a beautiful life — I am GRATEFUL!!! 🙏 ."

In the same post, he also celebrated Diaz's return to acting in her new project, Back In Action.

"ANOTHER MILESTONE happening TOMORROW!!! We are SO happy to see you…. BACK IN ACTION!!…. Congrats baby!!"

Madden and Diaz, 52, began dating in 2014 and tied the knot less than a year later. They now share two kids, the most recent of which they welcomed last year in March.

To share the news, the proud parents posted an Instagram photo of a piece of artwork, which read, "A little bird whispered to me."

In the caption, Madden revealed the news, writing: "We are blessed and excited to announce the birth of our Son, Cardinal Madden. He is awesome and we are all so happy he is here!"

He continued: "For the kid's safety and privacy we won't be posting any pictures — but he's a really cute. We are feeling so blessed and grateful. Sending much love from our fam to yours. Best wishes and Good Afternoon!!"

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A post shared by Benji Madden (@benjaminmadden)

They welcomed Cardinal four years after their first daughter, Raddix.

"We are so happy, blessed and grateful to begin this new decade by announcing the birth of our daughter," Diaz and Madden said at the time. "She has instantly captured our hearts and completed our family."

Diaz and Madden were introduced by the actress' close friend — and now sister-in-law — Nicole Richie. Just seven months later they were engaged, and in January 2015 they married.

Previously, Diaz wrote an essay for InStyle in which she made a rare declaration about their relationship, calling her husband "the greatest human being".

"Getting married to him was the best thing that ever happened to me," she said.

"My husband's the best. He's the greatest human being, and he's my great partner. Marriage is certainly hard, and it's a lot of work. You need somebody who's willing to do the work with you, because there's no 60-40 in marriage. It's 50-50, period. All the time.

"I don't know if I was ready [when I got married], but I knew Benji was special. He's just a good man. There's no bullsh*t. It's really refreshing. I'm really grateful for him."

Side note: Cameron Diaz is passionate about her relationship, wellness and… pubic hair? Post continues below.

During her wedding speech, Diaz addressed her previous assertions that she would never get married.

"I waited because I didn't want to settle," she said. "Now I got the best man ever. My special man. He's mine."

It was a whirlwind romance.

The pair make very few public appearances and aren't often gushy about each other in public, but in 2016 Diaz told Andy Cohen on Sirius XM Radio that none of her exes came close to Madden. Yep, not even Justin Timberlake or Jared Leto.

"I don't even remember any of that. Like that's the thing, that's how I know he's my husband because no one compares," she said.

Diaz told Cohen that before Madden she never believed people who said "when you know, you know". But after meeting him, everything changed.

"I was always like, 'What does that mean… what does that mean?' Then I was like 'Oh, I get it, you just know when you know, like you're my husband.'"

"Everything else just kind of like washes and slips away," she said.

"You realise like, 'Oh right, this is what the real thing is, this is what real love is and this is what commitment and devotion is. This is the person that you build your life with, and for me, it's like the rest of everything else just kind of like dissolves."

Madden occasionally shares loving messages about his wife on social media, and the pair always show their support for each other's business ventures.

When Diaz released The Longevity Book in 2016, Madden said he "could not be prouder of my bad ass wife".

"She wakes up everyday on a mission to try and make the world a better place. I'm always amazed by the courage, strength and vulnerability she shows, relentlessly encouraging other women to love themselves."

He's also honoured her in a very permanent way, getting a large tattoo of his wife's name on his chest.

This article was originally published in 2020, and has since been updated with new information.

Feature Image: Instagram/@benjaminmadden