The Hollywood couple welcomed their firstborn on Tuesday 30 September, and on Thursday her proud daddy made the big announcement.
"Mila and I would like to welcome Wyatt Isabelle Kutcher to the world," he said. "May your life be filled with wonder, love, laughter, health, happiness, curiosity and privacy."
In an interesting spin, the actor, 36, then shared a series of different baby photos, writing: "Can you guess which one is ours, or does it really matter? All babies are cute."
It's been a memorable year for Mila, 31, and Ashton.
In February it was revealed they were engaged, followed one month later by the news that Mila was pregnant with their first baby.
In recent weeks, the actress has been seen preparing for her little girl's arrival, attending prenatal pilates and yoga classes. She has also revealed her plans to become a full-time mummy.
"To me this job has always been a hobby that turned into a great profession, but I don’t eat and breathe acting," Mila told W magazine in July. "I'm sure Meryl Streep has a very different point of view. But I'm excited about being a full-time mum."
Mila Kunis and Ashton Kutcher welcomed their firstborn on 30th September
Ashton, meanwhile, has been doting on Mila in the build-up to the arrival of their first baby.
"Ashton is super excited," his Two and a Half Men co-star Jon Cryer recently told People.
"Ashton has even been excited every time we had a child around on set. He loves kids and could not be more stoked to have a child."