The 29-year-old took to Twitter to make the happy announcement, revealing when their baby is due to arrive.
"Baby number 3 is on the way …… January!! We are so happy and excited [sic]," Coleen gushed.
The fashion designer sparked pregnancy rumours earlier today, when she shared a holiday snap from her break to Barbados with Wayne and their sons Kai, five, and two-year-old Klay.
Looking happy and relaxed, Coleen showed off a noticeably fuller tummy which had fans speculating immediately.
No doubt Coleen and footballer Wayne, also 29, are hoping the new baby will be the little girl they've always dreamed of.
Speaking to Closer earlier this year, Coleen said: "I would love another baby! I don't mind whether it's a girl or a boy but I do think a little girl would complete our family.
"Wayne would love to have a girl because he grew up with brothers."
Congratulations to Coleen, Wayne, Kai and Klay!