The 27-year-old actress welcomed her second child, a baby girl, on Wednesday, her rep confirmed to ET.
Ivey Joan was born in Covington, Louisiana, weighing 7 lbs., 8 oz.
"We are beyond excited to welcome this beautiful baby girl to our family!" Spears told People, “Her middle name, Joan, is to honor my Aunt Sandra, who passed away 10 years ago from ovarian cancer. She was the most graceful woman I've ever known."
Spears' older sister, Britney Spears, tweeted her congratulations on the new addition, writing, "I could not be more excited to welcome baby Ivey to this world. Congrats to @jamielynnspears and the whole family - I love you all so much!!!"
Ivey is Spears' first child with husband Jamie Watson. She also is mother to a 9-year-old daughter, Maddie Briann, from her previous relationship with Casey Aldridge.
Spears revealed she was expecting her second child back in December with a sweet family pic posted to Instagram.
"Looks like we are starting off 2018 with another big milestone," she said at the time. "Sooo happy to announce that Maddie is FINALLY going to be a big sister. 2017 was filled with some of the biggest challenges of my life, as well as some of the biggest blessings, so I made a choice to lay low this year to focus on truly becoming my best self as a person and as an artist."
"During that time, I continued working on my music and telling my story, which has created some of my most honest work and I [CAN’T] wait to share that with you all very soon," she continued. "2018 is going to be filled with many milestones both personally and professionally."