"This makes my heart so happy .... ?," Tish wrote alongside the sweet snap. She also shared a second photo of just Miley and the "Achy Breaky Heart" crooner.
Now that the "secret's out," Miley's older sister, Brandi, also took to her Instagram Story to share how excited she was for her sister.
"So happy for you guys! Been a long time comin'!" she wrote alongside a black-and-white photo of the newlyweds hugging.
Miley and Liam tied the knot on Dec. 23. The former Disney Channel star confirmed the date on her Instagram, sharing photos of her and her new hubby.
A source told ET that "marriage has become such a topic of conversation in their relationship," adding, "Everyone is always asking them when, and now it's real, they did it! The gathering was small and intimate and rather spontaneous."
"They did some quick pre-planning before the holiday and decided that they didn’t want a big elaborate wedding. They truly wanted to keep it a secret," the source continued. “They just wanted the people most important in their lives present. It was so touching. They decided to do it at their home in Tennessee, as they have talked about in the past."
Meanwhile, a spokesperson for the Williamson County Clerk in Tennessee confirms to ET that the pair applied for a marriage license. The license is still going through the approval process.