Five News revealed that the 36-year-old welcomed her first son at a London hospital.
"Mother and baby are doing fine... Her colleagues here at Five News are delighted too - and we've sent our best wishes," commented a spokesperson for the show.
Husband Justin Bower said the couple are "thrilled" with the new arrival.
Kaplinsky is being covered by Matt Barbet and Isla Traquair while she takes maternity leave.