The overjoyed mother took to Instagram on Sunday evening to reveal the exciting news.
Alongside a snap of herself cradling her blossoming bump in a chic white, off-the-shoulder dress the 32-year-old penned: “On Wednesday, July 22nd I became a Mom.”
“It has without a doubt been the most profoundly beautiful time in my life but also emotionally, spiritually and physically challenging too....and I am so grateful for every second of it.”
“Brandon and I are taking care of our healthy, little baby girl, Eva James Jenner.”
James is shaping up to be a popular celeb name for girls after Blake Lively and Ryan Reynolds named their daughter James.
The reality TV couple, who often star in Keeping Up With The Kardashians and also perform in their self-titled band Brandon & Leah, announced they were expecting their first child in March.
Lean and Brandon will also star in Caitlyn Jenner's new TV show I Am Cait, however it's not yet known if the arrival of Caitlyn's granddaughter will be documented on the series.
No doubt music will be running through this little one’s veins already – her grandfather and Leah’s father is Eagles guitarist Don Felder.
Congratulations to the new family of three!
Watch footage from Leah's glamorous baby shower in May in the player below