The 44-year-old musician marked the occasion Wednesday by sharing a tribute to Diaz on Instagram.
Madden posted a photo of Diaz smiling for the camera while holding their cat. He called the actress his "best friend" and "best partner in everything" in the caption.
"I'm off line mostly these days, just working, painting, making things and doing family life, but I have grown to like my little tradition of coming back on special occasions to show love to my Queen- so today, it's a very Happy Birthday to my beautiful wife, best friend, best partner in everything, ride or die, greatest Mom to our little girl, @Avaline wine boss, family chef, advisor, collaborator and everything else. You do it all," Madden wrote.
"So grateful to have our family and I am one lucky man - I know that seems obvious but it really is nice to say it out loud now and then when you're feeling it," he said. "I love you -forever -always -yours -true love. Happy Birthday Cameron."
Diaz responded in the comments, writing, "There's no one else I would rather do this life with. We are so blessed.. I you with all my [heart] @benjaminmadden."
Madden and Diaz met through Madden's sister-in-law Nicole Richie and married at their Los Angeles home in January 2015. The couple announced the birth of their first child, daughter Raddix, in January 2020.
"We are so happy, blessed and grateful to begin this new decade by announcing the birth of our daughter, Raddix Madden," Diaz said on Instagram. "She has instantly captured our hearts and completed our family."
Madden said on his seventh wedding anniversary with Diaz in January 2022 that he "always dreamed of having a family like this."
"Happy, peaceful, consistent, loyal and unconditional equally filled with passion and depth," the star added. "Calling it a Honeymoon doesn't cover it. Real life. The only challenge we have is making time go slower cause life goes by fast in the happy lane."