The singer, 32, took to Twitter on Friday night (20 June) to post the adorable snap of River Rose, who is just days old.
Alongside the heartbreakingly cute picture of River Rose having a little nap in an old-fashioned style pram, Kelly wrote an emotional message about the newborn.
The American Idol winner said: "Here is our beautiful baby girl River Rose; 6lbs 6oz, 18 inches, and the greatest thing on the planet :)."
She also added a thank you to the photographer, writing: "Thank you so much @Archetype_Photo @kobyb for the amazing pictures of our little girl!! Once again, y'all knocked it out of the park!!"
Kelly and her talent manager husband Brandon Blackstock welcomed their first child together on Thursday 12 June.
The proud new mummy announced her baby's arrival in a tweet saying: "Our baby girl River Rose Blackstock arrived on June 12th! Thank you everyone for all of your well wishes! Brandon and I are on cloud 9!!"
The 'My Life Would Suck Without You' star announced her pregnancy in November last year, then revealed her first child would be a girl that January.
Kelly is already a stepmother to Brandon's two children from his first marriage, Seth, seven, and Savannah, 11.
Kelly and Brandon married in a low-key ceremony in Tennessee last October and she made no secret of the fact she wanted kids.
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