In the pic, the newlyweds stand next next to a vintage blue station wagon with "Just Married" painted on the back window and tin cans tied to the bumper and trailing behind the car. Duff looks stunning in an elegant white Jenny Packham wedding gown while Koma rocks a truly dapper traditional tux.
Duff captioned the cute pic simply, "This." Shortly thereafter, Koma adorably replied "First!" in the comments.
Koma took to his own Instagram page to share the same photo, writing in the caption, "For the rest of forever... 12.21.19."
Not long after the pair shared their first pic as a married couple, Vogue took to Instagram to share an exclusive look at Duff trying on her gown for the first time.
"When @HilaryDuff married singer and record producer @MatthewKoma last night in their front yard in Los Angeles, she wore a @jennypackham dress, custom-made in London," the caption read. "Watch as we catch up with the bride-to-be in the days before her wedding, when Jenny had just shipped the dress from London to L.A."
Duff and Koma were first romantically linked in early 2017. They welcomed their first child together, daughter Banks Violet Bair, in October 2018. Duff is also mom to 7-year-old son Luca, whom she shares with her ex-husband, Mike Comrie.
Koma and Duff sparked marriage rumors in October, after the musician referred to the actress as his "wife" in an Instagram post.