The father-of-two shared a photo of Willow, 7, outside the hospital posing with her arm in a sling.
"Willz has her first ER trip today due to a crash and burn on the monkey bars," he wrote.
"She is tough as nails and left with a sprain."
Carey, 43, added the hashtags: #ProudPapa and #BubbleWrapYourKids.
Fans were quick to send their well-wishes to the little one.
"Awwww poor Willow! I hope she feels better soon! Those monkey bar wipeouts are no joke!," one wrote.
Another said, " I’m 40 and still crashin’ and burnin’ she’ll be ok! 💕 glad it’s just a sprain!"
Get better soon, Willow!