Willow Phoenix Buckley was born at 1:36 a.m. Sunday, at Cedars-Sinai Hospital in West Hollywood, People reported. She weighed 7 pounds, 5 ounces.
"Both baby, mother and father are doing well," Buckley's representatives said.
Buckley, 35, shared the news on Twitter, saying, "Greatest moment in my life happened at 136am this morning when my [fiancee] gave birth to our little angel Willow Phoenix Buckley #ProudDad."
The actor, who previously starred on "CSI: NY," announced in September that he and Ochse, an oncology nurse, were expecting.