The couple reportedly exchanged vows and wedding bands from Tiffany's in front of about 100 guests in Camarillo, CA, where many of DeWyze's loved ones traveled from the singer's hometown of Chicago.
According to People, Walsh walked down the aisle to "Who Would Have Known," a song DeWyze wrote solely for her.
"It's a personal song that will be on my next album," he said.
The bride reportedly wore a Lili Bridal strapless lace-embroidered gown fit for the vintage-inspired wedding, which also featured blush-colored roses and peonies.
"[My dress] was mermaid shaped because I look like a ridiculous cupcake in a ball gown," Walsh told People. "[At the reception], we also had vintage movie reels since I'm an actress and sheets of music that were rolled up and put in jars."
The newlyweds are reportedly set to honeymoon in Bali because Walsh has never been there.
DeWyze and Walsh got engaged in July 2011 after eight months of dating when DeWyze had proposed on a private yacht at Disney World.
The couple met in 2010 when DeWyze had selected Walsh to star in his "Sweet Serendipity" music video. They had their first date at a Los Angeles Lakers versus Chicago Bulls NBA basketball game shortly afterwards, and Walsh's butterflies apparently told her right away she was meant to become Mrs. DeWyze.
"When he took me home that night I called my mom and told her that I was going to marry him," said Walsh, who is taking her new husband's name. "I could feel it in my heart."
"When I realized I could be 100% percent myself around her all of the time I knew I wanted to be with her for the rest of my life," DeWyze added.
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