Marah Carey is completely winning Saint Patrick's Day.

The 45-year-old singer celebrated the Irish holiday on Thursday by rocking a dazzling green sequin gown, which she accessorized with a fur coat.

"Happy #Stpatricksday!!" Carey captioned the sexy Instagram pic.

WATCH: Mariah Carey Rocks Her Bikini Bod in St. Barts

Carey's been looking slimmer than ever as of late, while performing on her Sweet Fantasy tour. Her latest stop was in Glasgow, Scotland, on Tuesday, where she rocked a bedazzled bodysuit reminiscent of Jennifer Lopez's multiple sequin get-ups for the singer's "All I Have" Las Vegas residency.

... Pretty amazing, given Carey and J.Lo's rumored long-time feud.

The "Infinity" singer also impressively performed in sky-high platform boots, again flaunting her toned figure in a shiny black leotard and tights.

Could Carey's super slim physique be in preparation for her upcoming wedding to her fiance, billionaire businessman James Packer? The two got engaged in January, when Packer, 48, popped the question in New York City with a stunning 35-carat diamond and platinum engagement ring.

WATCH: See Mariah Carey's Massively Gorgeous 35-Carat Engagement Ring From James Packer

While Carey hasn't confirmed any details on her upcoming big day, we do know that Carey and Packer will be living together in an upscale gated community in Calabasas, California. The wealthy couple closed a deal to lease a mansion for $250,000 a month (or $3 million a year) in January, ET confirmed.

"The deal was done in just a few days," a source told ET. "The couple was not looking at homes for a long time. This is just the perfect place for Mariah and her family -- it's safe, it's secure, it's home."

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