Mackenzie, 22, shared a photo of their baby's sonogram in the emotional Instagram snap.
"Baby Girl Edwards is coming in January!" she captioned the pic.
Baby number two will join their son Jagger, who was born in October 2018.
Ryan, 31, shares a son with ex and fellow Teen Mom OG star Maci Bookout.
Mackenzie also has a son from a previous relationship.
Ryan and Mackenzie got engaged in December 2016 before officially tying the knot in May 2017.
Are you surprised that Ryan and Mackenzie are having a second child? Sound off in the comments!