The star, who received a Grammy Award nomination for his appearance on Lil Nas X's "Old Town Road" earlier this week, shared an adorable video on the social networking site, of himself with Miley as a toddler during an appearance on a talk show.
"Happy Birthday @MileyCyrus!!! Love you so much," the country singer captioned the clip, showing Miley in her dad's arms, wearing a purple jacket and a ribbon in her hair.
Meanwhile, the star's beau Cody Simpson and family and close friends came together to celebrate her big day, after she'd been lying low since undergoing vocal cord surgery.
Miley's older sister Brandi Cyrus took to her Instagram Stories to share a video of Miley wearing a crown on her head while blowing out the candles on her cake.
Cody later took to Instagram to share a video of him and Miley along with the caption, "Happy birthday baby. Thanks for being you."
And the Australian singer's mum Angie also headed to Instagram to send her best wishes to her son's girlfriend, sharing a black and white snap of the happy couple with the caption, "Happy Birthday Miley. Have a magical day and can't wait to be with you both very soon."