Diaz and Madden married in January 2015 and have a daughter, Raddix, who turns four years old in December.
On The Tonight Show, Diaz shared her awe at seeing Madden recently perform with Good Charlotte at When We Were Young Festival in Las Vegas and remembering her husband is "a giant rock star."
"He's like, you know, Benj at home with being the best dad ever and running all of his businesses, and he just gets up there and he's like, 'Yeah, all right, pyro,'" she said.
Diaz said Madden creates and sings songs to their daughter, which she called "the sweetest thing ever."
"I'm like, 'You need to do a kids album,' because he has, like, the best songs. They play in my head all the time because he sings them to her, and she knows the words, and it's the sweetest thing ever. It really is. It's so -- it kills me."
Madden marked Diaz's 51st birthday on Instagram in August, calling the actress his "best friend" and "best partner in everything."