"Yes it's true! WAHOOOOOOO!!! Molly is going to be a MOM and TY a BIG BROTHER! YIPPEEEEEEE!" Mesnick, 36, tweeted Thursday, confirming his wife's pregnancy.
Added pregnant Malaney, 28, "We couldn't be more excited about the pint size peanut on the way."
The couple married in front of 250 family members and friends -- and ABC cameras -- in February 2010, shortly after Mesnick famously dumped "Bachelor" fiancée Melissa Rycroft on national TV in order to date Malaney.
He proposed during a vacation in New Zealand where they fell in love during an overnight "Bachelor" date. After presenting Malaney with a bouquet of wildflowers, Mesnick snuck the engagement ring -- a 1.2-plus carat, antique cushion-cut stone with small diamonds along the platinum band -- into the bottom of her champagne glass.