The former Lizzie McGuire star announced her split from hockey player Mike in January 4 but neither had filed official papers to end their marriage.
According to TMZ, those papers were filed by Hilary last week.
The website claims she cited "irreconcilable differences" and listed the date of separation as January 2013. It alleges she's seeking primary custody of their son Luca, who is nearly three.
Hilary and Mike have not confirmed the reports.
In a statement announcing their split two years ago, a rep said: "They remain best friends and will continue to be in each other's lives. They are dedicated to loving and parenting their amazing son, and ask for privacy at this time."
Despite separating after four years of marriage, they had remained close friends and were frequently seen in each other's company, with and without their son Luca.
As recently as September last year, Hilary had hinted a reunion wasn't completely off the cards, telling Aussie radio show Kyle & Jackie O: "We're uncoupled for now... If there wasn't a chance of getting back [together], we would have filed for divorce..."
"I talk about this so much and I don't want to talk about this any more. But I spoke with [Mike] this morning, we really care a lot about each other. Whatever happens, happens. Once we're tired of doing this, we'll make a choice."
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