Cameron Diaz and Benji Madden welcome baby girl

Cameron Diaz and Benji Madden have secretly welcomed a baby daughter.

The 47-year-old actress and her Good Charlotte rocker husband made the surprise announcement on Friday via Instagram.

"Happy New Year from the Maddens!" their joint message reads. "We are so happy, blessed and grateful to begin this new decade by announcing the birth of our daughter, Raddix Madden.

"She has instantly captured our hearts and completed our family. While we are overjoyed to share this news, we also feel a strong instinct to protect our little one's privacy. So we won't be posting pictures or sharing any more details, other than the fact that she is really, really cute!! Some would even say RAD.

"From our family to all of yours, we're sending our love and best wishes for a Happy New Year and Happy New Decade... Sincerely, Cameron & Benj."

Cameron and Benji, 40, wed in 2015. Raddix is the stars' first child.