The 28-year-old actress confirmed she was dating her personal trainer last month.
Hilary Duff and her boyfriend, Jason Walsh, are red carpet official!
The adorable couple attended George Clooney, Rande Gerber, and Mike Meldman's annual Casamigos Tequila Halloween Party in Beverly Hills, California, on Friday.
WATCH: Hilary Duff on Personal Trainer Boyfriend Jason Walsh: 'We Have a Lot of Fun Together'
While the evening marked the first public appearance for the pair, it was their controversial Thanksgiving-themed costumes that garnered most of the attention.
The Younger star sported a black fedora as part of her pilgrim costume, while her beau was dressed as a Native American.
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Just before the party, Duff previewed her costume on Instagram.
"Sooooo the fake gun for my pilgrim costume came," she captioned the pic. "Don't think it's quite big enough ??."
Just one day before the trainer turned up at the Halloween fete, Chris Hemsworth apologized for wearing a Lone Ranger costume to a New Year's Eve party last year, noting that he "was stupidly unaware of the offence this may have caused and the sensitivity around this issue."
ET has reached out to Walsh's rep.
RELATED: Hilary Duff Channels Her 'Casper Meets Wendy' Character, 20 Years Later
Duff and Walsh, who first confirmed they were dating in September, brought their romance to Instagram just two weeks ago.
"Date night with J ❤," the 28-year-old actress wrote alongside the sweet PDA-filled snap.
This isn't the first time a relatively new set of lovebirds has stepped out at a Casamigos party. Last year's soiree was where Gwen Stefani and Blake Shelton made their debut as a couple.
Relive that grand moment in the video below.
