The "Tonight Show" star just welcomed his second child with wife Nancy Juvonen, a baby girl named Frances Cole Fallon.
"Frances Cole Fallon officially entered the world at 8:45 a.m. on Dec. 3, weighing 5 lbs., 11 oz. and is 18.5 inches long," a rep for the 40-year-old told PEOPLE.
"Their new addition joins big sister, Winnie Rose, [16 months]. The couple opted to keep their baby joy to themselves until their new daughter made her official debut. Both Fallon babies were born via surrogate," the statement concluded.
We're sure little Winnie (below) will love being a big sis to baby Frances!
This has been a great week for the comedian -- Fallon was also just named Entertainment Weekly's 2014 Entertainer of the Year!
Check out the galleries above to see more celeb baby names and cute kids!