The couple became engaged over the Christmas (12) break and celebrated its impending nuptials during a lavish party at Los Angeles eatery Mr. Chow on Monday (28Jan13), a representative confirmed to UsMagazine.com.
A source says, "They got engaged over the holidays. They've known each other for quite some time, as their paths have crossed off-and-on over the past 20 years."
It will be the third marriage for both TV veterans - the former Little House on the Prairie star and mother-of-two's exes include actor Bo Brinkman and Bruce Boxleitner, who she divorced in 2011. Busfield, who has three children of his own, was previously wed to Radha Delmarter and Jenny Meriwin.
The former child star, 46, wed actor Bruce Boxleitner, 60, in 1995 and they are parents to 15-year-old son Michael, in addition to three children from previous relationships.
A statement from the actress reads, "We have loved each other for a very long time and we share four incredible sons together. On behalf of our family we ask to be allowed our privacy during this very difficult time."
Gilbert was previously married to Bo Brinkman, father of her 21-year-old son Dakota.