The Will and Grace star ended her 11 year marriage to producer Daniel Zelman earlier this year, but the pair remain close and committed to their seven-year-old son Roman.
Her representative said: "They privately separated earlier this year. The decision was mutual and they remain supportive of one another and committed to raising their son as a family."
Despite their break-up, Debra and Daniel - who met on their first day at New York University in 1990 - still live together.
A source said: "They have been separated the better part of the year but continue to live together in New York for Roman. It's very amicable."
Debra has previously claimed the reason they stayed together was because they met when they were young and grew as a couple.
She said: "I think we're lucky we met really young when we were both students and hopeful about the future and excited by the romance of the struggle then.
"I think we just have a real respect for each other as individuals, and I think we're lucky as we grew up together we grew closer instead of further away. Our goals and priorities and perspectives became more in line with each other than when we first met."