Hart took to Instagram to pen a heartwarming post about the rocker, accompanied with a black-and-white throwback pic of the two rocking stylish, '20s-inspired ensembles.
"Happy birthday to my amazing wife @pink," the former freestyle motocross racer captioned it. "We have been together for almost 15 years, and I've been lucky enough to watch her grow up into the best mother, fierce business woman, great friend, and amazing partner."
"I love you so much baby!!" his adorable message continued. "You are like a fine wine baby."
Pink and Hart, 41, celebrated their 10th wedding anniversary in January. The two met at the 2001 X Games in Philadelphia, Pennsylvania, and in 2005, the pop star adorably proposed to Hart on a race track in Mammoth Lakes, California. As Hart was coming up on his third lap during the Pro 250 class finals, Pink held up a pit board that read, "Will You Marry Me?" followed by "Serious!" He quickly pulled off the track, letting his fellow racers pass him, and said "Yes!"
Although the couple has had their fair share of ups and downs -- they briefly separated in February 2008 but got back together in April 2009 -- the two are still head over heels in love with each other and their 5-year-old daughter, Willow.
While chatting with ET last November, Pink joked that Willow is "mean" like her, and "cute" like her dad. Hear more in the video below.