They welcomed their first child, a son named Camden John, on Wednesday. He weighed 8 lbs., 9 oz., and measured 21 inches.
In a statement, the couple said: "Love has truly been redefined for both of us."
The Lacheys wed in 2011. Last month, 38-year-old Nick Lachey reunited with his band, 98 Degrees, on the "Today" show and in concert in Hershey, Pa. He also competed on NBC's reality competition show "Stars Earn Stripes."
Vanessa Lachey, 31, is a co-host on ABC's "Wipeout."
The birth was reported on People.com