Justin Bieber's mom, Pattie Mallette, is over the moon about her son's huge baby announcement -- but she's even more excited about becoming a grandma.
Mallette posted a video Thursday, mere hours after Justin and his wife, Hailey, broke the news they're preparing for their first child.
The famous couple kissed and embraced as Hailey showed off her baby bump in a wedding gown. Other images showed Justin snapping photos of his pregnant wife.
And Mallette couldn't be happier ... in her IG video, Mallette said she's been anxiously waiting for the big reveal so she could share that she's gonna be a gramma, happily shouting, "Oh my goodness!”
She also predicted Justin and Hailey would be the "best parents ever" before praising God.
Our sources tell us Hailey is just over 6 months along and expecting to give birth to their little kiddo by late summer.
In her caption, Mallette gushed even more about her gramma status, while congratulating the lovebirds on their soon-to-be born cutie pie.
By the way, the name and gender of the tot has not been disclosed yet ... but we're sure that'll be coming down the pike in the near future.