The newborn arrived Wednesday morning, Jimmy’s representative told People magazine in a statement.
The couple, who welcomed both Frances Cole and now 16-month-old daughter Winnie Rose via surrogate, chose to keep the news about their baby a secret until the special day arrived.
“The couple opted to keep their baby joy to themselves until their new daughter, Frances Cole, made her official debut,” the statement read.
The “Tonight Show” host and his wife became parents for the first time in July 2013.
Fallon, 40, and Juvonen, 47, got married in 2007 after meeting on the set of the movie “Fever Pitch”.