Gilbert, 48, and former Thirtysomething star Timothy Busfield, 55, are headed to the altar, the actress's rep confirms to PEOPLE.
"They are engaged and both are incredibly happy," the rep says. The two got engaged over the holidays, adds a source.
The mother of two, who was previously married to Bo Brinkman and Bruce Boxleitner, was dating Thierry Gauchet at the time she shimmied with Maksim Chmerkovskiy on Dancing with the Stars.
Busfield, who has also been married twice, has three children from previous relationships.