The actress shared a sweet tribute via Instagram on Monday, posting a photo of her and her husband floating in a zero-gravity chamber.
“Happy Birthday my love!” Kidman, 53, captioned the snap. “Love is in the air.”
Urban later posted a video of a smash-cake, that he received as a gift, being crushed by a baseball bat.
“Best birthday ever,” he wrote alongside the slow-motion video.
Meanwhile, Urban celebrated his wife’s latest show, The Undoing, in an Instagram Story.
“There’s nothing like a thriller — who did it? What is going on???? addictive excellence!!!!! Congrats to you baby — and all the incredible cast!!!!!!!” Urban wrote of the HBO miniseries.
Kidman recently opened up about her early days in Hollywood and how her biggest challenge at the start of her career was being single.
“When I was alone, when I was single, I think [fame] was much harder because there wasn’t a shield,” she explained to The Sydney Morning Herald. “There wasn’t a place to go and to work through it, with a partner.
“I was lucky because my sister would come. I remember her flying to Cannes [in 2001] because it’s frightening walking up that red carpet with all that scrutiny, feeling very insecure and not quite sure where to go or how to survive.”