McGowan, 39, wore a strapless white dress and a veil for her special day, with her hair up in a bun. She also carried a bouquet of pink flowers down the aisle. The couple's vows lasted 15 minutes. A New Orleans swing band then played as guests were escorted to a cocktail area with stunning white lights surrounding a courtyard.
The Tell-Tale Heart star and Detail first announced their engagement in July after more than a year of dating, with the actress previously telling Us that she thought her artist beau was "magic."
"He's made me a better woman. And I've made him a better man!" she shared with Us at the premiere of Mademoiselle C in NYC on Sept. 6.
The actress was previously twice-engaged — to Machete Kills director Robert Rodriguez in 2007 and before that, to rocker Marilyn Manson in 1998 — but this is her first marriage.
Next up? The happy newlyweds are heading to Tahiti for their honeymoon, according to McGowan. "I've never been," she previously told Us. "I've always dreamed of having one of those little huts over the water."
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