Lachey's wife, Lea, gave birth to their daughter Thursday, publicist Holly Shakoor said in a statement. The baby is the couple's first child.
"Mom, dad and baby are all happy and healthy," the statement said. No other details were released.
Lachey, 29, a former singer in the pop band 98 Degrees, won the second season of ABC's ballroom hit, "Dancing With the Stars."
He will co-host the 2006 Miss USA pageant in Baltimore on April 21.