People magazine reported Monday that documents to initiate a legal split were filed that afternoon at the Bucks County Courthouse in Doylestown, Penn.
That development was followed by a heavily-promoted episode of the couple's TLC reality series "Jon & Kate Plus 8" Monday evening in which the couple said they would separate.
The network had promised a from the couple, whose increasingly troubled 10-year marriage has dominated the series in recent weeks as well as fueling a firestorm of tabloid coverage. Published accounts have alleged infidelity by both partners, accusations they both deny.
The Gosselins' announcement raises new questions about the future of "Jon & Kate," which, now in its fifth season, is TLC's most popular series.
But both parents say the show will continue, with their segments of the show filmed separately.
The split comes after Jon Gosselin was reportedly seen in New York on Friday. Earlier than that, rumors of both Gosselins cheating have swirled (but have been denied) and the two have publicly acknowledged on their realtiy show, "Jon & Kate Plus 8," that they were having marital problems.
"We're navigating a difficult time," the couple said in a statement after the May 25 premiere of their show's fifth season, which brought in a record-breaking 9.8 million viewers. During that episode, Kate tearfully said, "Parents of multiples have triple the divorce rate. I was thinking we were going to beat that. I don't know if I can say that anymore."