"So blessed today to see my little man come into the world", he wrote on Instagram along with a photo of him and his wife holding their new bundle of joy on Friday.
The country superstar had just started his set when Stephen Paddock, 64, began firing shots from the Mandalay Bay hotel.
Kerr shared all the details in her caption, revealing that Memphis was born weighing 9 pounds, 5 ounces.
Later that night, once Brittany had time to reflect on the day, she posted her own thoughts on Instagram.
Congratulations Jason and Brittany!
This year has held its share of pain and challenges for Jason Aldean, which makes the birth of little Memphis Aldean such a big blessing.
Brittany Aldean, who Wednesday the country singer back in March 2015, announced that she was pregnant in May. I can't wait to see what life has in store for this kid.
He was born on December 1, weighing in at nine pounds and five ounces, and both Jason and Brittany headed straight to their Instagram pages to share their happiness over their new arrival. The biggest rollercoaster we have ever been on, without a doubt!
He also has two daughters from his previous marriage to Jessica Ann Ussery. "We will never take one moment for granted & can't wait to meet you, sweet baby!"