'American Idol' Winner Kris Allen Welcomes Baby No. 2: 'It's a Girl!'

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Kris Allen celebrated his first Father's Day as a father of two this year.

The American Idol season eight winner and wife Katy welcomed baby No. 2 on Saturday -- and the couple waited until then to find out the baby's sex, as Allen told ET last month, "We don't know what it's going to be, which we're really excited about."

Well, it's a girl!

"It's A Girl!! Welcome to the world Rosie. Oh man...I am done. She's already got me figured out I think," Allen wrote alongside an adorable photo of his daughter. "Excuse me while I go learn how to braid hair on YouTube for the next 13 years...cuz that's how long it's gonna take me. #itsagirl #rosie"

WATCH: Kelly Clarkson Shares New Pic of Baby Boy for Father's Day, Thanks Husband Brandon Blackstock for 'Being Such a Great Dad'

The couple tied the knot in 2008 and has a son, Oliver, who turns three in July. When ET caught up with Allen, he said Oliver was "excited" about becoming a big brother.

"I think he knows there's a baby coming," he said. "I don't know if he knows where it's coming from, but I don't think he should at this time. He is getting excited about it. Family is starting to buy certain things for him, and so I think he realized, 'Oh, this is for the baby.' So, hopefully he's a good big brother!"

The "Live Like We're Dying" singer also revealed how becoming a dad changed "everything."

"It's weird. You think you know how to love until you have kids and then you're like, 'Holy crap, why am I crying all the time?'" Allen explained. "I'm not a crier, I haven't cried ever. Now, any kind of commercial that deals with father and son I'm done -- totally done for...It has taught me real emotion and love and I think it was something I thought I knew before, but that's a deeper thing."

In other new dads news, Eddie Redmayne and his wife, Hannah Bagshawe, welcomed their own baby girl, Iris, last week. Find out more in the video below!