Khoé Kardashian Odom is among the other members of the famous family also expressing excitement.
"I am BEYOND thrilled to fiiiiinally be able to share with all of you the fabulous news that my beautiful big sister Kourtney is expecting yet again! Can you believe it?! Masey is going to be a big brother!" Khloé posted on her blog today.
"We are all so overjoyed by this wonderful news and are counting down the minutes until we get to meet the newest member of our family," she added before offering up some kind words about Kourt's parenting skills.
"Kourtney is the greatest mom in the world and I am so proud of the woman she has become," Khloé wrote. "I can't wait to see her with a kid in each arm! She'll be a pro. LOL. And if this next baby is anything like Mason, then we will truly be the luckiest family in the world."
"Congratulations, Kourt, Scott and Mason!!!! I love you all more than anything!"
Mom Kris Jenner, too, couldn't contain her feelings.
"A HUGE big CONGRATULATIONS to Kourtney and Scott!" she exclaimed on her blog. "Nothing is more precious or dear to my heart than my children and grandchildren and we couldn't be happier to share this amazing news!! Another amazing addition to our family and we feel completely blessed!!"
"PRAISE GOD from whom all blessings flow!!! You guys are amazing parents and we love you soooooooo much!!!!!!!!!!!!!!!!"