"Can’t believe it’s our 13th wedding anniversary. Who would have thought two misfits like us could pull it off!!! I’m very grateful for you, baby. We have created an amazing life and family together. I love you," he wrote.
The loved-up couple tied the knot in 2006 after Pink popped the question while the former Motorcross star was racing around the track.
She held up a poster reading: "Will You Marry Me?" and Hart gladly accepted.
Since then, the pair have had two children, daughter, Willow, 7, and Jameson, 2.
The 39-year-old singer has been very vocal about her relationship with Hart, and revealed the secret behind their long-lasting marriage.
"There are moments where I look at [Hart] and he is the most thoughtful, logical, constant…he’s like a rock. He’s a good man. He’s a good dad. He’s just the kind of dad I thought he’d be and then some," she told Guardian.
"And then I’ll look at him and go: I’ve never liked you. There’s nothing I like about you. We have nothing in common. I don’t like any of the shit you like. I don’t ever wanna see you again. Then two weeks later I’m like, things are going so good, you guys... Monogamy is work! But you do the work and it’s good again.”