Christmas came early for the Nashville actress who gave birth to a baby girl on Tuesday (9 December).
The happy couple have named their daughter Kaya Evdokia Klitschko.
In a statement to People, the couple confirmed the news and revealed the newborn weighed in at 7lbs,14oz.
They said: "We are over the moon and madly in love!"
Hayden, 25, announced her engagement to heavyweight boxing champion Wladimir, 38, in October 2013.
She then confirmed her pregnancy in August 2014 while taking part in the ALS Ice Bucket charity challenge.
Addressing her fans in a video moments before she dunked herself in cold water, Hayden picked her nominations to do the fundraiser - and she nominated her unborn baby!
"I accept my ALS Challenge. I renominate Kacey Musgraves - you're not getting out of this, Wladimir Klitschko and my unborn child," she said.
She has previously admitted that she felt born to be a mother.
A huge congratulations to the happy couple!
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See the celebrity couples who have welcomed babies in 2014:
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