Port took to Instagram on Thursday to share the happy news, alongside a pic of her adorably tiny baby bump.
"Oh hey! Just standing by the window in my underwear, with a BABY in my belly!!!" she wrote alongside the cute pic. "DM me if you know what I'm supposed to do with this thing for however many years I'm supposed to be in charge. Check out my blog for a little letter from me & Timmy and for more behind the scenes of this crazy journey!!!! We are sooooo excited!!!! ?: @colemoser."
Port and Rosenman, an associate producer on her Hills spinoff, The City, tied the knot in November 2015, in a gorgeous Palm Springs, California, ceremony.
ET caught up with the 31-year-old fashion designer last May, where she opened up about starting a family.
"I'm happily married. I'd love to eventually start a family and become a mom," she revealed. "[It won't be] happening in the super near future, but definitely something that I would love to be able to do."
Port isn't the only Hills alum expecting a bundle of joy. In fact, Port's BFF, Lauren Conrad, announced that she was pregnant with her first child last month in a special New Year's message to fans.