Teigen took to social media on Thursday to make the announcement.
"Somebody's herrrrrrre!" Teigan tweeted, followed with baby bottle and smiling emojis.
"Happy pregnant Chrissy is gone".
The 32-year-old model and foodie confirmed the couple's happy news on Twitter by simply writing: 'Somebody's herrrrrre!'
"Luna, what's in here", Teigen asked her daughter.
"I don't think Luna has a concept of exactly what it means to have a little sibling yet", Legend said.
The loved up couple have previously been open about their struggle to conceive naturally, however, they announced the they were expecting their second baby last November, after undergoing IVF.More news: First lady Melania 'doing really well' after medical procedure: Donald Trump
The couple became parents for the second time.
Teigen and her singer husband, 39, got to meet their son early as he was expected in June.
He told People: 'Luna's gonna be an issue.
"I'm so ready for it", she said. "We've seen fertility doctors".
Congratulations to John Legend and his wife, Chrissy as they welcome this new bundle of joy.
Teigen and Legend tied the knot in a gorgeous September 2013 wedding in Lake Como, Italy.