Dykstra, 23, is the son of New York Mets and Philadelphia Phillies star Lenny Dykstra.
"So this just happened," Sigler said in a message posted Monday with a photo of herself, looking shocked and showing off her new ring, while her fiance grins.
"She said yes!!!" Dykstra separately tweeted.
People.com said the couple have been together for about a year.
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