Miley and Liam got their license in Williamson County, Tennessee on December 18 ... 5 days before they got hitched at Miley's home outside of Nashville.

Miley and Liam were super secret in the lead-up to the wedding Sunday night, but they made it clear from videos and pics they got hitched.

Liam's brother -- Chris and Luke -- were on hand. Miley's mom, Tish, dad, Billy Ray along with Miley's sisters, Noah and Brandi, were also on hand.

One of the pics -- showing Miley in her wedding dress and Liam in a tux with white shoes -- bears the caption, "10 years later ..." That lines up with the first time they met, on the set of the Nicholas Sparks movie, "The Last Song."

The party was relaxed and fun ... you see the Hemsworth bros doing celebratory shots, with "Mr" and Mrs" balloons in the background.