The 19 Kids and Counting couple's son Josh and his wife Anna became parents to their second child, a baby son, on Wednesday evening, according to the Today show.
A name for the new arrival, who weighed 8lbs 5oz, has not been released yet.
Josh and Anna announced the pregnancy on the Today show back in November surrounded by their "excited" family.
Josh is the eldest son of Jim Bob and Michelle, who have 18 other children between his age of 23 and their youngest daughter Josie, who celebrated her first birthday in December.
Josh and Anna are already parents to daughter Mackynzie Renée Duggar, who was born via a home birth in October 2009. They discovered they were expecting their second child on Mackynzie's first birthday.
19 Kids: First Grandson airs Sunday at 8/7c on TLC.
Watch Matt Lauer announce the new Duggar baby below: