The couple took to Twitter to announce that they were expecting a baby girl less than two years after Vanessa gave birth to their son Camden John.
"Can't think of a better way to celebrate 3 years of marriage to my beautiful Vanessa Lachey than this! family," Nick tweeted with a picture of a child.
Vanessa retweeted with the addition "It's a girl."
Nick and Vanessa met on the set of his music video "What's Left of Me" in 2006. They got married in 2011.