In a series of sweet snaps, the actor, 43, made his relationship with Bosworth, 39, Instagram official on Wednesday.
In the carousel of photos, captioned simply with a green heart and Irish flag, Long posted a series of selfies with the Blue Crush star, sharing a pint of Ireland's famous beer.
After the first shot, where the two are seen sipping out of a glass, the following photos showcase the two rocking mustaches made from the beer's foam.
"I'm the luckiest. 🍀✨😘," Bosworth commented on the post.
Last week, the Accepted actor opened up about his relationship — his first time directly naming Bosworth as his partner — on an episode of the Dear Chelsea podcast episode, saying that being "in love" is "such a wonderful feeling."
"Am I allowed to say her name?" host Chelsea Handler, asked Long before he agreed, and she identified the actress as his special someone.
"I've never had anything like this before; I've never experienced this," he added. "So it's something I want to protect and keep, you know?"
Long confirmed he had a girlfriend on a December 2021 episode of his podcast Life is Short with Justin Long though did not identify Bosworth by name.
In recent months, Long and Bosworth have been snapped packing on the PDA, including sharing a passionate kiss on a beach in Hawaii, where they traveled in April for former InStyle editor-in-chief Laura Brown's wedding. They were also photographed with their arms around each other while out walking together in New York City.
Bosworth and Long previously spent time together last year filming an unnamed project in Arkansas. In May 2021, Bosworth posted a glowing tribute to Long after wrapping the film with him.
"Holy moly @justinlong you are a truly spectacular / fun / funny / kind / rare / thoughtful / totally. fckn. rad human being. 🌻," she wrote on Instagram, posting a carousel of photos that opened with a playful snapshot of her in Long's arms. "THANK YOU for lifting us up ... you kept it light & full of laughter daily, even through the toughest moments. You gnome how much I love ya 💛 (sorry had to ;)"
Long commented on the post, where he jokingly replied, "That's ALL you wrote about me??? Well ... I admire your restraint."