Hebert, who starred on The Bachelorette's seventh season, made the big announcement on Instagram Monday, while also revealing she's pregnant with a girl, who will join big brother Fordham Rhys, 19 months.
"I can't hold it in any longer... My heart is bursting with love now that we're #ClearblueConfirmed!" Hebert captioned a photo of a blackboard that reads "Ashley + JP + Ford + Baby Girl = [Heart]" with little pink shoes on it.
"These booties are just the start, can't wait to stock up on cute tutus and sparkles for my #babygirl! #ClearbluePartner."
Rosenbaum added on his own social media page, "100% excited... My face says I'm 78% nervous b/c #ItsAGirl."
In February, Hebert admitted to People there was "talk" and "action" of "more babies" in her future with Rosenbaum.
"We're rockin'!" Hebert said at the time.
Hebert, 32, and Rosenbaum, 39, got engaged on The Bachelorette in 2011 and wed on live television in December 2012. The couple announced they were expecting their first child in March 2014 and then Hebert gave birth to Fordham in September of that year.